feature/add-i18n-support (#167)

Co-authored-by: Michael Hoennig <michael@hoennig.de>
Reviewed-on: https://dev.hostsharing.net/hostsharing/hs.hsadmin.ng/pulls/167
Reviewed-by: Marc Sandlus <marc.sandlus@hostsharing.net>

src/main/java/net/hostsharing/hsadminng/config/MessageTranslator.java

@@ -0,0 +1,40 @@
+package net.hostsharing.hsadminng.config;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.MessageSource;
+import org.springframework.stereotype.Service;
+import org.springframework.web.context.annotation.RequestScope;
+
+import jakarta.servlet.http.HttpServletRequest;
+import java.util.Locale;
+
+@Service
+@RequestScope
+public class MessageTranslator {
+
+    @Autowired
+    private HttpServletRequest httpRequest;
+
+    @Autowired
+    private MessageSource messageSource;
+
+    public String translateTo(final Locale locale, final String messageKey, final Object... args) {
+        try {
+            // we don't use the method which also takes a default message right away ...
+            final var translatedMessage = messageSource.getMessage(messageKey, args, locale);
+            return translatedMessage;
+        } catch (final Exception e) {
+            final var defaultMessage = messageKey.replace("'", "''");
+            final var translatedMessage = messageSource.getMessage(messageKey, args, defaultMessage, locale);
+            if (locale != Locale.ENGLISH) {
+                // ... because we want to add a hint that the translation is missing, even if placeholders got replaced
+                return translatedMessage + " [" + locale + " translation missing]";
+            }
+            return translatedMessage;
+        }
+    }
+
+    public String translate(final String messageKey, final Object... args) {
+        return translateTo(httpRequest.getLocale(), messageKey, args);
+    }
+}

src/main/java/net/hostsharing/hsadminng/config/MessagesResourceConfig.java

@@ -0,0 +1,17 @@
+package net.hostsharing.hsadminng.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.support.ResourceBundleMessageSource;
+
+@Configuration
+public class MessagesResourceConfig {
+    @Bean
+    public ResourceBundleMessageSource messageSource() {
+        final var source = new ResourceBundleMessageSource();
+        source.setBasenames("i18n/messages");
+        source.setDefaultEncoding("UTF-8");
+        return source;
+    }
+
+}

src/main/java/net/hostsharing/hsadminng/config/RealCasAuthenticator.java

@@ -1,6 +1,7 @@
 package net.hostsharing.hsadminng.config;
 
 import io.micrometer.core.annotation.Timed;
+import lombok.RequiredArgsConstructor;
 import lombok.SneakyThrows;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.beans.factory.annotation.Value;
@@ -17,6 +18,7 @@ import java.io.IOException;
 
 // HOWTO add logger
 @Slf4j
+@RequiredArgsConstructor
 public class RealCasAuthenticator implements CasAuthenticator {
 
     @Value("${hsadminng.cas.server}")
@@ -25,8 +27,11 @@ public class RealCasAuthenticator implements CasAuthenticator {
     @Value("${hsadminng.cas.service}")
     private String serviceUrl;
 
+    private final MessageTranslator messageTranslator;
+
     private final RestTemplate restTemplate = new RestTemplate();
 
+
     @SneakyThrows
     @Timed("app.cas.authenticate")
     public String authenticate(final HttpServletRequest httpRequest) {
@@ -52,7 +57,7 @@ public class RealCasAuthenticator implements CasAuthenticator {
 
     private Document verifyServiceTicket(final String serviceTicket) throws SAXException, IOException, ParserConfigurationException {
         if ( !serviceTicket.startsWith("ST-") ) {
-            throwBadCredentialsException("Invalid authorization ticket");
+            throwBadCredentialsException("unknown authorization ticket");
         }
 
         final var url = casServerUrl + "/cas/p3/serviceValidate" +
@@ -69,12 +74,13 @@ public class RealCasAuthenticator implements CasAuthenticator {
     private String extractUserName(final Document verification) {
 
         if (verification.getElementsByTagName("cas:authenticationSuccess").getLength() == 0) {
-            throwBadCredentialsException("CAS service ticket could not be verified");
+            throwBadCredentialsException("CAS service-ticket could not be verified");
         }
         return verification.getElementsByTagName("cas:user").item(0).getTextContent();
     }
 
-    private void throwBadCredentialsException(final String message) {
-        throw new BadCredentialsException(message);
+    private void throwBadCredentialsException(final String messageKey) {
+        final var translatedMessage = messageTranslator.translate(messageKey);
+        throw new BadCredentialsException(translatedMessage);
     }
 }

src/main/java/net/hostsharing/hsadminng/config/RetroactiveTranslator.java

@@ -0,0 +1,11 @@
+package net.hostsharing.hsadminng.config;
+
+/**
+ * Makes it possible to translate messages which got created by external sources (libraries, database, etc.)
+ * without i18n support.
+ */
+public interface RetroactiveTranslator {
+
+    boolean canTranslate(final String message);
+    String translate(final String message);
+}

src/main/java/net/hostsharing/hsadminng/config/WebSecurityConfig.java

@@ -26,6 +26,9 @@ public class WebSecurityConfig {
     @Autowired
     private CasAuthenticationFilter authenticationFilter;
 
+    @Autowired
+    private MessageTranslator messageTranslator;
+
     @Bean
     @Profile("!test")
     public SecurityFilterChain securityFilterChain(final HttpSecurity http) throws Exception {
@@ -55,7 +58,7 @@ public class WebSecurityConfig {
     @Bean
     @Profile("realCasAuthenticator")
     public CasAuthenticator realCasServiceTicketValidator() {
-        return new RealCasAuthenticator();
+        return new RealCasAuthenticator(messageTranslator);
     }
 
     @Bean

src/main/java/net/hostsharing/hsadminng/errors/CustomErrorResponse.java

@@ -11,7 +11,7 @@ import java.time.LocalDateTime;
 @Getter
 public class CustomErrorResponse {
 
-    static ResponseEntity<CustomErrorResponse> errorResponse(
+    static ResponseEntity<CustomErrorResponse> customErrorResponse(
             final WebRequest request,
             final HttpStatus httpStatus,
             final String message) {
@@ -21,13 +21,13 @@ public class CustomErrorResponse {
 
     static String firstMessageLine(final Throwable exception) {
         if (exception.getMessage() != null) {
-            return line(exception.getMessage(), 0);
+            return stripTechnicalDetails(exception.getMessage());
         }
         return "ERROR: [500] " + exception.getClass().getName();
     }
 
-    static String line(final String message, final int lineNo) {
-        return message.split("\\r|\\n|\\r\\n", 0)[lineNo];
+    static String stripTechnicalDetails(final String message) {
+        return message.split("\\r|\\n|\\r\\n", 0)[0];
     }
 
     @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "yyyy-MM-dd hh:mm:ss")
@@ -41,12 +41,12 @@ public class CustomErrorResponse {
 
     private final String message;
 
-    CustomErrorResponse(final String path, final HttpStatus status, final String message) {
+    CustomErrorResponse(final String path, final HttpStatus status, final String rawMessage) {
+        // HOWTO: debug serverside error response - set a breakpoint here
         this.timestamp = LocalDateTime.now();
         this.path = path;
         this.statusCode = status.value();
         this.statusPhrase = status.getReasonPhrase();
-        // HOWTO: debug serverside error response - set a breakpoint here
-        this.message = message.startsWith("ERROR: [") ? message : "ERROR: [" + statusCode + "] " + message;
+        this.message = rawMessage.startsWith("ERROR: [") ? rawMessage : "ERROR: [" + statusCode + "] " + rawMessage;
     }
 }

src/main/java/net/hostsharing/hsadminng/errors/ReferenceNotFoundException.java

@@ -1,19 +1,36 @@
 package net.hostsharing.hsadminng.errors;
 
+import net.hostsharing.hsadminng.config.MessageTranslator;
+
 import java.util.UUID;
 
+import static java.util.Locale.ENGLISH;
+
 public class ReferenceNotFoundException extends RuntimeException {
 
+    private final String TRANSLATABLE_MESSAGE = "{0} \"{1}\" not found";
+
+    private final MessageTranslator translator;
+
     private final Class<?> entityClass;
+    private final String entityClassDisplayName;
     private final UUID uuid;
-    public <E> ReferenceNotFoundException(final Class<E> entityClass, final UUID uuid, final Throwable exc) {
+
+    public <E> ReferenceNotFoundException(final MessageTranslator translator, final Class<E> entityClass, final UUID uuid, final Throwable exc) {
         super(exc);
+        this.translator = translator;
         this.entityClass = entityClass;
+        this.entityClassDisplayName = DisplayAs.DisplayName.of(entityClass);
         this.uuid = uuid;
     }
 
     @Override
     public String getMessage() {
-        return "Cannot resolve " + entityClass.getSimpleName() +" with uuid " + uuid;
+        return translator.translateTo(ENGLISH, TRANSLATABLE_MESSAGE, entityClassDisplayName, uuid);
+    }
+
+    @Override
+    public String getLocalizedMessage() {
+        return translator.translate(TRANSLATABLE_MESSAGE, entityClassDisplayName, uuid);
     }
 }

src/main/java/net/hostsharing/hsadminng/errors/RestResponseEntityExceptionHandler.java

@@ -1,8 +1,13 @@
 package net.hostsharing.hsadminng.errors;
 
+import lombok.RequiredArgsConstructor;
+import net.hostsharing.hsadminng.config.MessageTranslator;
+import net.hostsharing.hsadminng.config.RetroactiveTranslator;
 import org.iban4j.Iban4jException;
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.core.NestedExceptionUtils;
 import org.springframework.dao.DataIntegrityViolationException;
+import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.HttpStatusCode;
@@ -23,62 +28,67 @@ import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExcep
 import jakarta.persistence.EntityNotFoundException;
 import jakarta.validation.ValidationException;
 import java.util.*;
-import java.util.regex.Pattern;
+import java.util.function.Function;
 
 import static net.hostsharing.hsadminng.errors.CustomErrorResponse.*;
 
 @ControllerAdvice
+@RequiredArgsConstructor
 // HOWTO handle exceptions to produce specific http error codes and sensible error messages
 public class RestResponseEntityExceptionHandler
         extends ResponseEntityExceptionHandler {
 
+    @Autowired
+    private final MessageTranslator messageTranslator;
+
+    @Autowired(required = false)
+    private final List<RetroactiveTranslator> retroactiveTranslators;
+
     @ExceptionHandler(DataIntegrityViolationException.class)
     protected ResponseEntity<CustomErrorResponse> handleConflict(
             final RuntimeException exc, final WebRequest request) {
 
-        final var rawMessage = NestedExceptionUtils.getMostSpecificCause(exc).getMessage();
-        var message = line(rawMessage, 0);
-        if (message.contains("violates foreign key constraint")) {
-            return errorResponse(request, HttpStatus.BAD_REQUEST, line(rawMessage, 1).replaceAll(" *Detail: *", ""));
-        }
-        return errorResponse(request, HttpStatus.CONFLICT, message);
+        final var fullMaybeLocalizedMessage = localizedMessage(NestedExceptionUtils.getMostSpecificCause(exc));
+        final var sprippedMaybeLocalizedMessage = stripTechnicalDetails(fullMaybeLocalizedMessage);
+        return errorResponse(request, HttpStatus.CONFLICT, sprippedMaybeLocalizedMessage);
     }
 
     @ExceptionHandler(JpaSystemException.class)
     protected ResponseEntity<CustomErrorResponse> handleJpaExceptions(
             final RuntimeException exc, final WebRequest request) {
-        final var message = line(NestedExceptionUtils.getMostSpecificCause(exc).getMessage(), 0);
-        return errorResponse(request, httpStatus(exc, message).orElse(HttpStatus.INTERNAL_SERVER_ERROR), message);
+        final var fullMaybeLocalizedMessage = localizedMessage(NestedExceptionUtils.getMostSpecificCause(exc));
+        final var sprippedMaybeLocalizedMessage = stripTechnicalDetails(fullMaybeLocalizedMessage);
+        return errorResponse(request, httpStatus(exc, sprippedMaybeLocalizedMessage).orElse(HttpStatus.INTERNAL_SERVER_ERROR), sprippedMaybeLocalizedMessage);
     }
 
     @ExceptionHandler(NoSuchElementException.class)
     protected ResponseEntity<CustomErrorResponse> handleNoSuchElementException(
             final RuntimeException exc, final WebRequest request) {
-        final var message = line(NestedExceptionUtils.getMostSpecificCause(exc).getMessage(), 0);
-        return errorResponse(request, HttpStatus.NOT_FOUND, message);
+        final var fullMaybeLocalizedMessage = localizedMessage(NestedExceptionUtils.getMostSpecificCause(exc));
+        final var sprippedMaybeLocalizedMessage = stripTechnicalDetails(fullMaybeLocalizedMessage);
+        return errorResponse(request, HttpStatus.NOT_FOUND, sprippedMaybeLocalizedMessage);
     }
 
     @ExceptionHandler(ReferenceNotFoundException.class)
     protected ResponseEntity<CustomErrorResponse> handleReferenceNotFoundException(
             final ReferenceNotFoundException exc, final WebRequest request) {
-        return errorResponse(request, HttpStatus.BAD_REQUEST, exc.getMessage());
+        return errorResponse(request, HttpStatus.BAD_REQUEST, localizedMessage(exc));
     }
 
     @ExceptionHandler({ JpaObjectRetrievalFailureException.class, EntityNotFoundException.class })
     protected ResponseEntity<CustomErrorResponse> handleJpaObjectRetrievalFailureException(
             final RuntimeException exc, final WebRequest request) {
-        final var message =
-                userReadableEntityClassName(
-                        line(NestedExceptionUtils.getMostSpecificCause(exc).getMessage(), 0));
-        return errorResponse(request, HttpStatus.BAD_REQUEST, message);
+        final var localizedMessage = localizedMessage(NestedExceptionUtils.getMostSpecificCause(exc));
+        final var sprippedMaybeLocalizedMessage = stripTechnicalDetails(localizedMessage);
+        return errorResponse(request, HttpStatus.BAD_REQUEST, sprippedMaybeLocalizedMessage);
     }
 
     @ExceptionHandler({ Iban4jException.class, ValidationException.class })
     protected ResponseEntity<CustomErrorResponse> handleValidationExceptions(
             final Throwable exc, final WebRequest request) {
-        final String fullMessage = NestedExceptionUtils.getMostSpecificCause(exc).getMessage();
-        final var message = exc instanceof MultiValidationException ? fullMessage : line(fullMessage, 0);
-        return errorResponse(request, HttpStatus.BAD_REQUEST, message);
+        final var localizedMessage = localizedMessage(NestedExceptionUtils.getMostSpecificCause(exc));
+        final var sprippedMaybeLocalizedMessage = exc instanceof MultiValidationException ? localizedMessage : stripTechnicalDetails(localizedMessage);
+        return errorResponse(request, HttpStatus.BAD_REQUEST, sprippedMaybeLocalizedMessage);
     }
 
     @ExceptionHandler(Throwable.class)
@@ -96,15 +106,16 @@ public class RestResponseEntityExceptionHandler
 
         final var response = super.handleExceptionInternal(exc, body, headers, statusCode, request);
         return errorResponse(request, HttpStatus.valueOf(statusCode.value()),
-                Optional.ofNullable(response.getBody()).map(Object::toString).orElse(firstMessageLine(exc)));
+                Optional.ofNullable(response).map(HttpEntity::getBody).map(Object::toString).orElse(firstMessageLine(exc)));
     }
 
     @Override
     @SuppressWarnings("unchecked,rawtypes")
     protected ResponseEntity handleHttpMessageNotReadable(
             HttpMessageNotReadableException exc, HttpHeaders headers, HttpStatusCode status, WebRequest request) {
-        final var message = line(exc.getMessage(), 0);
-        return errorResponse(request, HttpStatus.BAD_REQUEST, message);
+        final var localizedMessage = localizedMessage(exc);
+        final var sprippedMaybeLocalizedMessage = stripTechnicalDetails(localizedMessage);
+        return errorResponse(request, HttpStatus.BAD_REQUEST, sprippedMaybeLocalizedMessage);
     }
 
     @Override
@@ -139,37 +150,26 @@ public class RestResponseEntityExceptionHandler
                 .flatMap(Collection::stream)
                 .filter(FieldError.class::isInstance)
                 .map(FieldError.class::cast)
-                .map(fieldError -> fieldError.getField() + " " + fieldError.getDefaultMessage() + " but is \""
-                        + fieldError.getRejectedValue() + "\"")
+                .map(toEnrichedFieldErrorMessage())
                 .toList();
         return errorResponse(request, HttpStatus.BAD_REQUEST, errorList.toString());
     }
 
-
-    private String userReadableEntityClassName(final String exceptionMessage) {
-        final var regex = "(net.hostsharing.hsadminng.[a-z0-9_.]*.[A-Za-z0-9_$]*Entity) ";
-        final var pattern = Pattern.compile(regex);
-        final var matcher = pattern.matcher(exceptionMessage);
-        if (matcher.find()) {
-            final var entityName = matcher.group(1);
-            final var entityClass = resolveClass(entityName);
-            if (entityClass.isPresent()) {
-                return (entityClass.get().isAnnotationPresent(DisplayAs.class)
-                        ? exceptionMessage.replace(entityName, entityClass.get().getAnnotation(DisplayAs.class).value())
-                        : exceptionMessage.replace(entityName, entityClass.get().getSimpleName()))
-                        .replace(" with id ", " with uuid ");
-            }
-
-        }
-        return exceptionMessage;
+    private Function<FieldError, String> toEnrichedFieldErrorMessage() {
+        final var translatedButIsLiteral = messageTranslator.translate("but is");
+        // TODO.i18n: the following does not work in all languages, e.g. not in right-to-left languages
+        return fieldError -> fieldError.getField() + " " + fieldError.getDefaultMessage() +
+                " " + translatedButIsLiteral + " " + optionallyQuoted(fieldError.getRejectedValue());
     }
 
-    private static Optional<Class<?>> resolveClass(final String entityName) {
-        try {
-            return Optional.of(ClassLoader.getSystemClassLoader().loadClass(entityName));
-        } catch (ClassNotFoundException e) {
-            return Optional.empty();
+    private String optionallyQuoted(final Object value) {
+        if (value == null) {
+            return "null";
         }
+        if (value instanceof Number) {
+            return value.toString();
+        }
+        return "\"" + value + "\"";
     }
 
     private Optional<HttpStatus> httpStatus(final Throwable causingException, final String message) {
@@ -187,4 +187,25 @@ public class RestResponseEntityExceptionHandler
         return Optional.empty();
     }
 
+    private String localizedMessage(final Throwable throwable) {
+        // most libraries seem to provide the localized message in both properties, but just for the case:
+        return throwable.getLocalizedMessage() != null ? throwable.getLocalizedMessage() : throwable.getMessage();
+    }
+
+    private String tryTranslation(final String message) {
+
+        for ( RetroactiveTranslator rtx: retroactiveTranslators ) {
+            if (rtx.canTranslate(message)) {
+                return rtx.translate(message);
+            }
+        }
+        return message;
+    }
+
+    private ResponseEntity<CustomErrorResponse> errorResponse(
+            final WebRequest request,
+            final HttpStatus httpStatus,
+            final String maybeTranslatedMessage) {
+        return customErrorResponse(request, httpStatus, tryTranslation(maybeTranslatedMessage));
+    }
 }

src/main/java/net/hostsharing/hsadminng/hs/hosting/asset/HsHostingAssetTranslations.java

@@ -0,0 +1,40 @@
+package net.hostsharing.hsadminng.hs.hosting.asset;
+
+import net.hostsharing.hsadminng.config.MessageTranslator;
+import net.hostsharing.hsadminng.config.RetroactiveTranslator;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+
+// HOWTO translate messages which got created without i18n support, in this case in a PostgreSQL constraint trigger
+@Service
+public class HsHostingAssetTranslations implements RetroactiveTranslator {
+
+    public static final String ERROR_400_PREFIX = "ERROR: [400] ";
+
+    @Autowired
+    private MessageTranslator messageTranslator;
+
+    @Override
+    public boolean canTranslate(final String message) {
+        return message.equals("ERROR: [400] coop assets transaction would result in a negative balance of assets");
+    }
+
+    @Override
+    public String translate(final String message) {
+        // it's guaranteed to be the same message, for which canTranslate(...) returned true
+        // and in this case it's just one
+        return ERROR_400_PREFIX + messageTranslator.translate(message.substring(ERROR_400_PREFIX.length()));
+
+        // HOWTO extract variable parts from a messages which got created without i18n support:
+        //  final var regex = "(?<propertyName>[^ ]+) (?<propertyValue>.+) not found";
+        //  final var pattern = Pattern.compile(regex);
+        //  final var matcher = pattern.matcher(message);
+        //
+        //  if (matcher.matches()) {
+        //      final var propertyName = matcher.group("propertyName");
+        //      final var propertyValue = matcher.group("propertyValue");
+        //      return messageTranslator.translate("", propertyName, propertyValue);
+        //  }
+    }
+}

src/main/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HostingAssetEntityValidator.java

@@ -145,7 +145,7 @@ public abstract class HostingAssetEntityValidator extends HsEntityValidator<HsHo
         if (assetEntity.getIdentifier() == null ||
                 !expectedIdentifierPattern.matcher(assetEntity.getIdentifier()).matches()) {
             return List.of(
-                    "'identifier' expected to match '" + expectedIdentifierPattern + "', but is '" + assetEntity.getIdentifier()
+                    "'identifier' expected to match '" + expectedIdentifierPattern + "' but is '" + assetEntity.getIdentifier()
                             + "'");
         }
         return Collections.emptyList();

src/main/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsIPv6NumberHostingAssetValidator.java

@@ -28,7 +28,7 @@ class HsIPv6NumberHostingAssetValidator extends HostingAssetEntityValidator {
         final var violations = super.validateEntity(assetEntity);
 
         if (!isValidIPv6Address(assetEntity.getIdentifier())) {
-            violations.add("'identifier' expected to be a valid IPv6 address, but is '" + assetEntity.getIdentifier() + "'");
+            violations.add("'identifier' expected to be a valid IPv6 address but is '" + assetEntity.getIdentifier() + "'");
         }
 
         return violations;

src/main/java/net/hostsharing/hsadminng/hs/office/coopassets/HsOfficeCoopAssetsTransactionController.java

@@ -2,6 +2,7 @@ package net.hostsharing.hsadminng.hs.office.coopassets;
 
 import io.micrometer.core.annotation.Timed;
 import io.swagger.v3.oas.annotations.security.SecurityRequirement;
+import net.hostsharing.hsadminng.config.MessageTranslator;
 import net.hostsharing.hsadminng.context.Context;
 import net.hostsharing.hsadminng.errors.MultiValidationException;
 import net.hostsharing.hsadminng.hs.office.generated.api.v1.api.HsOfficeCoopAssetsApi;
@@ -30,7 +31,6 @@ import java.util.function.BiConsumer;
 
 import static java.util.Optional.ofNullable;
 import static net.hostsharing.hsadminng.hs.office.coopassets.HsOfficeCoopAssetsTransactionType.REVERSAL;
-import static net.hostsharing.hsadminng.hs.office.coopassets.HsOfficeCoopAssetsTransactionType.TRANSFER;
 import static net.hostsharing.hsadminng.hs.office.generated.api.v1.model.HsOfficeCoopAssetsTransactionTypeResource.CLEARING;
 import static net.hostsharing.hsadminng.hs.office.generated.api.v1.model.HsOfficeCoopAssetsTransactionTypeResource.DEPOSIT;
 import static net.hostsharing.hsadminng.hs.office.generated.api.v1.model.HsOfficeCoopAssetsTransactionTypeResource.DISBURSAL;
@@ -50,6 +50,9 @@ public class HsOfficeCoopAssetsTransactionController implements HsOfficeCoopAsse
     @Autowired
     private EntityManagerWrapper emw;
 
+    @Autowired
+    private MessageTranslator messageTranslator;
+
     @Autowired
     private HsOfficeCoopAssetsTransactionRepository coopAssetsTransactionRepo;
 
@@ -131,33 +134,32 @@ public class HsOfficeCoopAssetsTransactionController implements HsOfficeCoopAsse
         MultiValidationException.throwIfNotEmpty(violations);
     }
 
-    private static void validateDebitTransaction(
+    private void validateDebitTransaction(
             final HsOfficeCoopAssetsTransactionInsertResource requestBody,
             final ArrayList<String> violations) {
         if (List.of(DEPOSIT, HsOfficeCoopAssetsTransactionTypeResource.ADOPTION).contains(requestBody.getTransactionType())
                 && requestBody.getAssetValue().signum() < 0) {
-            violations.add("for %s, assetValue must be positive but is \"%.2f\"".formatted(
+            violations.add(messageTranslator.translate("for transactionType={0}, assetValue must be positive but is {1,number,#0.00}",
                     requestBody.getTransactionType(), requestBody.getAssetValue()));
         }
     }
 
-    private static void validateCreditTransaction(
+    private void validateCreditTransaction(
             final HsOfficeCoopAssetsTransactionInsertResource requestBody,
             final ArrayList<String> violations) {
         if (List.of(DISBURSAL, HsOfficeCoopAssetsTransactionTypeResource.TRANSFER, CLEARING, LOSS)
                 .contains(requestBody.getTransactionType())
                 && requestBody.getAssetValue().signum() > 0) {
-            violations.add("for %s, assetValue must be negative but is \"%.2f\"".formatted(
+            violations.add(messageTranslator.translate("for transactionType={0}, assetValue must be negative but is {1,number,#0.00}",
                     requestBody.getTransactionType(), requestBody.getAssetValue()));
         }
     }
 
-    private static void validateAssetValue(
+    private void validateAssetValue(
             final HsOfficeCoopAssetsTransactionInsertResource requestBody,
             final ArrayList<String> violations) {
         if (requestBody.getAssetValue().signum() == 0) {
-            violations.add("assetValue must not be 0 but is \"%.2f\"".formatted(
-                    requestBody.getAssetValue()));
+            violations.add(messageTranslator.translate("assetValue must not be 0"));
         }
     }
 
@@ -221,26 +223,32 @@ public class HsOfficeCoopAssetsTransactionController implements HsOfficeCoopAsse
             final HsOfficeMembershipEntity membership = ofNullable(emw.find(
                     HsOfficeMembershipEntity.class,
                     resource.getMembershipUuid()))
-                    .orElseThrow(() -> new EntityNotFoundException("membership.uuid %s not found".formatted(
-                            resource.getMembershipUuid())));
+                    .orElseThrow(() -> new EntityNotFoundException(
+                            messageTranslator.translate(
+                                "{0} \"{1}\" not found", "membership.uuid", resource.getMembershipUuid())));
             entity.setMembership(membership);
         }
 
         if (entity.getTransactionType() == REVERSAL) {
             if (resource.getRevertedAssetTxUuid() == null) {
-                throw new ValidationException("REVERSAL asset transaction requires revertedAssetTx.uuid");
+                throw new ValidationException(messageTranslator.translate(
+                        "a REVERSAL asset transaction requires specifying a revertedAssetTx.uuid"));
             }
             final var revertedAssetTx = coopAssetsTransactionRepo.findByUuid(resource.getRevertedAssetTxUuid())
-                    .orElseThrow(() -> new EntityNotFoundException("revertedAssetTx.uuid %s not found".formatted(
+                    .orElseThrow(() -> new EntityNotFoundException(messageTranslator.translate(
+                            "{0} \"{1}\" not found",
+                            "revertedAssetTx.uuid",
                             resource.getRevertedAssetTxUuid())));
             revertedAssetTx.setReversalAssetTx(entity);
             entity.setRevertedAssetTx(revertedAssetTx);
             if (resource.getAssetValue().negate().compareTo(revertedAssetTx.getAssetValue()) != 0) {
-                throw new ValidationException("given assetValue=" + resource.getAssetValue() +
-                        " but must be negative value from reverted asset tx: " + revertedAssetTx.getAssetValue());
+                throw new ValidationException(
+                        messageTranslator.translate(
+                                "given assetValue {0,number,#0.00} must be the negative value of the reverted asset transaction: {1,number,#0.00}",
+                                resource.getAssetValue(), revertedAssetTx.getAssetValue()));
             }
 
-            if (revertedAssetTx.getTransactionType() == TRANSFER) {
+            if (revertedAssetTx.getTransactionType() == HsOfficeCoopAssetsTransactionType.TRANSFER) {
                 final var adoptionAssetTx = revertedAssetTx.getAdoptionAssetTx();
                 final var adoptionReversalAssetTx = HsOfficeCoopAssetsTransactionEntity.builder()
                         .transactionType(REVERSAL)
@@ -259,8 +267,9 @@ public class HsOfficeCoopAssetsTransactionController implements HsOfficeCoopAsse
         if (resource.getTransactionType() == HsOfficeCoopAssetsTransactionTypeResource.TRANSFER) {
             final var adoptingMembership = determineAdoptingMembership(resource);
             if ( entity.getMembership() == adoptingMembership) {
-                throw new ValidationException("transferring and adopting membership must be different, but both are " +
-                        adoptingMembership.getTaggedMemberNumber());
+                throw new ValidationException(messageTranslator.translate(
+                        "transferring and adopting membership must be different, but both are {0}",
+                        adoptingMembership.getTaggedMemberNumber()));
             }
             final var adoptingAssetTx = createAdoptingAssetTx(entity, adoptingMembership);
             entity.setAdoptionAssetTx(adoptingAssetTx);
@@ -271,34 +280,45 @@ public class HsOfficeCoopAssetsTransactionController implements HsOfficeCoopAsse
         final var adoptingMembershipUuid = resource.getAdoptingMembershipUuid();
         final var adoptingMembershipMemberNumber = resource.getAdoptingMembershipMemberNumber();
         if (adoptingMembershipUuid != null && adoptingMembershipMemberNumber != null) {
-            throw new ValidationException(
-                    // @formatter:off
-                resource.getTransactionType() == HsOfficeCoopAssetsTransactionTypeResource.TRANSFER
-                    ? "either adoptingMembership.uuid or adoptingMembership.memberNumber can be given, not both"
-                    : "adoptingMembership.uuid and adoptingMembership.memberNumber must not be given for transactionType="
-                            + resource.getTransactionType());
-                // @formatter:on
+            // @formatter:off
+            final var message =  messageTranslator.translate(
+                    resource.getTransactionType() == HsOfficeCoopAssetsTransactionTypeResource.TRANSFER
+                            ? "either {0} or {1} must be given, not both"
+                            : "neither {0} nor {1} must be given for transactionType={2}",
+                            "adoptingMembership.uuid",
+                            "adoptingMembership.memberNumber",
+                            resource.getTransactionType());
+            // @formatter:on
+            throw new ValidationException(message);
         }
 
         if (adoptingMembershipUuid != null) {
             final var adoptingMembership = membershipRepo.findByUuid(adoptingMembershipUuid);
             return adoptingMembership.orElseThrow(() ->
-                    new ValidationException(
-                            "adoptingMembership.uuid='" + adoptingMembershipUuid + "' not found or not accessible"));
+                    new ValidationException(messageTranslator.translate(
+                            "{0} \"{1}\" not found or not accessible",
+                            "adoptingMembership.uuid",
+                            adoptingMembershipUuid)));
         }
 
         if (adoptingMembershipMemberNumber != null) {
             final var adoptingMemberNumber = Integer.valueOf(adoptingMembershipMemberNumber.substring("M-".length()));
             final var adoptingMembership = membershipRepo.findMembershipByMemberNumber(adoptingMemberNumber);
             return adoptingMembership.orElseThrow( () ->
-                    new ValidationException("adoptingMembership.memberNumber='" + adoptingMembershipMemberNumber
-                            + "' not found or not accessible")
-            );
+                    new ValidationException(
+                            messageTranslator.translate(
+                                    "{0} \"{1}\" not found or not accessible",
+                                    "adoptingMembership.memberNumber",
+                                    adoptingMembershipMemberNumber)));
         }
 
         throw new ValidationException(
-                "either adoptingMembership.uuid or adoptingMembership.memberNumber must be given for transactionType="
-                        + HsOfficeCoopAssetsTransactionTypeResource.TRANSFER);
+                messageTranslator.translate(
+                        "either {0} or {1} must be given for transactionType={2}",
+                        "adoptingMembership.uuid",
+                        "adoptingMembership.memberNumber",
+                        resource.getTransactionType()
+                        ));
     }
 
     private HsOfficeCoopAssetsTransactionEntity createAdoptingAssetTx(

src/main/java/net/hostsharing/hsadminng/hs/office/partner/HsOfficePartnerController.java

@@ -2,6 +2,7 @@ package net.hostsharing.hsadminng.hs.office.partner;
 
 import io.micrometer.core.annotation.Timed;
 import io.swagger.v3.oas.annotations.security.SecurityRequirement;
+import net.hostsharing.hsadminng.config.MessageTranslator;
 import net.hostsharing.hsadminng.context.Context;
 import net.hostsharing.hsadminng.errors.ReferenceNotFoundException;
 import net.hostsharing.hsadminng.hs.office.contact.HsOfficeContactFromResourceConverter;
@@ -45,6 +46,9 @@ public class HsOfficePartnerController implements HsOfficePartnersApi {
     @Autowired
     private StrictMapper mapper;
 
+    @Autowired
+    private MessageTranslator translator;
+
     @Autowired
     private HsOfficeContactFromResourceConverter<HsOfficeContactRealEntity> contactFromResourceConverter;
 
@@ -236,7 +240,7 @@ public class HsOfficePartnerController implements HsOfficePartnersApi {
         try {
             return em.getReference(entityClass, uuid);
         } catch (final Throwable exc) {
-                throw new ReferenceNotFoundException(entityClass, uuid, exc);
+                throw new ReferenceNotFoundException(translator, entityClass, uuid, exc);
         }
     }
 

src/main/java/net/hostsharing/hsadminng/hs/validation/ValidatableProperty.java

@@ -217,8 +217,8 @@ public abstract class ValidatableProperty<P extends ValidatableProperty<?, ?>, T
                 //noinspection unchecked
                 validate(result, (T) propValue, propsProvider);
             } else {
-                result.add(propertyName + "' is expected to be of type " + type.getSimpleName() + ", " +
-                        "but is of type " + propValue.getClass().getSimpleName());
+                result.add(propertyName + "' is expected to be of type " + type.getSimpleName() +
+                        " but is of type " + propValue.getClass().getSimpleName());
             }
         }
         return result;

src/main/java/net/hostsharing/hsadminng/ping/PingController.java

@@ -1,8 +1,9 @@
 package net.hostsharing.hsadminng.ping;
 
+import net.hostsharing.hsadminng.config.MessageTranslator;
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.security.core.context.SecurityContextHolder;
 import org.springframework.stereotype.Controller;
-import org.springframework.web.bind.annotation.RequestHeader;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.bind.annotation.ResponseBody;
@@ -11,11 +12,15 @@ import org.springframework.web.bind.annotation.ResponseBody;
 @Controller
 public class PingController {
 
+    @Autowired
+    private MessageTranslator messageTranslator;
+
     @ResponseBody
     @RequestMapping(value = "/api/ping", method = RequestMethod.GET)
-    public String ping(
-            @RequestHeader(name = "assumed-roles", required = false) String assumedRoles
-    ) {
-        return "pong " + SecurityContextHolder.getContext().getAuthentication().getName() + "\n";
+    public String ping() {
+        final var userName = SecurityContextHolder.getContext().getAuthentication().getName();
+        // HOWTO translate text with placeholders - also see in resource files i18n/messages_*.properties.
+        final var translatedMessage = messageTranslator.translate("pong {0} - in English", userName);
+        return translatedMessage + "\n";
     }
 }

src/main/java/net/hostsharing/hsadminng/rbac/generator/RbacSpec.java

@@ -1069,7 +1069,7 @@ public class RbacSpec {
          */
         public static SQL fetchedBySql(final String sql) {
             if ( !sql.startsWith("SELECT ${columns}") ) {
-                throw new IllegalArgumentException("SQL SELECT expression must start with 'SELECT ${columns}', but is: " + sql);
+                throw new IllegalArgumentException("SQL SELECT expression must start with 'SELECT ${columns}' but is: " + sql);
             }
             validateExpression(sql);
             return new SQL(sql, Part.SQL_QUERY);

src/main/resources/i18n/messages_de.properties

@@ -0,0 +1,26 @@
+# This file must be in UTF-8 encoding. Check if you see umlauts or garbage: äöüÄÖÜß.
+# HINT IntelliJ IDEA shows unused keys in gray.
+
+pong\ {0}\ -\ in\ English=pong {0} - auf Deutsch
+
+# config (including authorization)
+CAS\ service-ticket\ could\ not\ be\ verified=CAS Service-Ticket konnte nicht verifiziert werden
+unknown\ authorization\ ticket=unbekanntes Autorisierungs-Ticket
+
+# general validations
+{0}\ "{1}"\ not\ found={0} "{1}" nicht gefunden
+{0}\ "{1}"\ not\ found\ or\ not\ accessible={0} "{1}" nicht gefunden oder nicht zugänglich
+but\ is=ist aber
+
+# office.coop-assets
+either\ {0}\ or\ {1}\ must\ be\ given=entweder {0} oder {1} muss angegeben werden
+either\ {0}\ or\ {1}\ must\ be\ given,\ not\ both=entweder {0} oder {1} muss angegeben werden, nicht beide
+either\ {0}\ or\ {1}\ must\ be\ given\ for\ transactionType\={2}=für transactionType={2} muss entweder {0} oder {1} angegeben werden
+neither\ {0}\ nor\ {1}\ must\ be\ given\ for\ transactionType\={2}=für transactionType={2} darf weder {0} noch {1} angegeben werden
+assetValue\ must\ not\ be\ 0=assetValue darf nicht 0 sein
+for\ transactionType\={0},\ assetValue\ must\ be\ positive\ but\ is\ {1,number,#0.00}=für transactionType={0}, muss assetValue positiv sein, ist aber {1,number,#0.00}
+for\ transactionType\={0},\ assetValue\ must\ be\ negative\ but\ is\ {1,number,#0.00}=für transactionType={0}, muss assetValue negativ sein, ist aber {1,number,#0.00}
+given\ assetValue\ {0,number,#0.00}\ must\ be\ the\ negative\ value\ of\ the\ reverted\ asset\ transaction\:\ {1,number,#0.00}=assetValue={0,number,#0.00} muss dem negativen Wert des Wertes der stornierten Geschäftsguthaben-Transaktion entsprechen: {1,number,#0.00}
+a\ REVERSAL\ asset\ transaction\ requires\ specifying\ a\ revertedAssetTx.uuid=eine REVERSAL Geschäftsguthaben-Transaktion erfordert die Angabe einer revertedAssetTx.uuid
+transferring\ and\ adopting\ membership\ must\ be\ different,\ but\ both\ are\ {0}=übertragende und annehmende Mitgliedschaft müssen unterschiedlich sein, aber beide sind {0}
+coop\ assets\ transaction\ would\ result\ in\ a\ negative\ balance\ of\ assets=Geschäftsguthaben-Transaktion würde zu einem negativen Geschäftsguthaben-Saldo führen

src/main/resources/i18n/messages_en.properties

@@ -0,0 +1,8 @@
+# This file must be in UTF-8 encoding. Check if you see umlauts or garbage: äöüÄÖÜß
+# HINT IntelliJ IDEA shows unused keys in gray.
+
+# If the English translation is identical to the translation-key, it does not need to be included here.
+# But in that case, you can NOT use a prefix - or the prefix would be shown to the user as well.
+# I'm not sure, though, if using the english default translations as keys is really a good idea.
+
+

src/test/java/net/hostsharing/hsadminng/config/CasAuthenticationFilterIntegrationTest.java

@@ -18,9 +18,11 @@ import org.springframework.http.HttpStatus;
 import org.springframework.test.context.ActiveProfiles;
 import org.springframework.test.context.TestPropertySource;
 
+
 import static com.github.tomakehurst.wiremock.client.WireMock.aResponse;
 import static com.github.tomakehurst.wiremock.client.WireMock.get;
 import static com.github.tomakehurst.wiremock.client.WireMock.urlEqualTo;
+import static java.util.Map.entry;
 import static net.hostsharing.hsadminng.config.HttpHeadersBuilder.headers;
 import static org.apache.commons.lang3.RandomStringUtils.randomAlphanumeric;
 import static org.assertj.core.api.Assertions.assertThat;
@@ -69,13 +71,13 @@ class CasAuthenticationFilterIntegrationTest {
         final var result = restTemplate.exchange(
                 "http://localhost:" + this.serverPort + "/api/ping",
                 HttpMethod.GET,
-                new HttpEntity<>(null, headers("Authorization", "ST-valid")),
+                new HttpEntity<>(null, headers(entry("Authorization", "ST-valid"))),
                 String.class
         );
 
         // then
         assertThat(result.getStatusCode()).isEqualTo(HttpStatus.OK);
-        assertThat(result.getBody()).isEqualTo("pong " + username + "\n");
+        assertThat(result.getBody()).startsWith("pong " + username);
         // HOWTO assert log messages
         assertThat(capturedOutput.getOut()).containsPattern(
                 LogbackLogPattern.of(LogLevel.DEBUG, RealCasAuthenticator.class, "CAS-user: " + username));
@@ -97,7 +99,7 @@ class CasAuthenticationFilterIntegrationTest {
         final var result = restTemplate.exchange(
                 "http://localhost:" + this.serverPort + "/api/ping",
                 HttpMethod.GET,
-                new HttpEntity<>(null, headers("Authorization", "invalid")),
+                new HttpEntity<>(null, headers(entry("Authorization", "invalid"))),
                 String.class
         );
 

src/test/java/net/hostsharing/hsadminng/config/HttpHeadersBuilder.java

@@ -2,11 +2,16 @@ package net.hostsharing.hsadminng.config;
 
 import org.springframework.http.HttpHeaders;
 
+import java.util.Map;
+
 public class HttpHeadersBuilder {
 
-    public static HttpHeaders headers(final String key, final String value) {
-        final var headers = new HttpHeaders();
-        headers.set(key, value);
-        return headers;
+    @SafeVarargs
+    public static HttpHeaders headers(final Map.Entry<String, String>... headers) {
+        final var httpHeaders = new HttpHeaders();
+        for (Map.Entry<String, String> entry : headers) {
+            httpHeaders.set(entry.getKey(), entry.getValue());
+        }
+        return httpHeaders;
     }
 }

src/test/java/net/hostsharing/hsadminng/errors/RestResponseEntityExceptionHandlerUnitTest.java

@@ -1,5 +1,6 @@
 package net.hostsharing.hsadminng.errors;
 
+import net.hostsharing.hsadminng.config.MessageTranslator;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.junit.jupiter.params.ParameterizedTest;
@@ -20,6 +21,7 @@ import jakarta.persistence.EntityNotFoundException;
 import java.util.List;
 import java.util.NoSuchElementException;
 
+import static java.util.Collections.emptyList;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
@@ -27,7 +29,8 @@ import static org.mockito.Mockito.when;
 @ExtendWith(MockitoExtension.class)
 class RestResponseEntityExceptionHandlerUnitTest {
 
-    final RestResponseEntityExceptionHandler exceptionHandler = new RestResponseEntityExceptionHandler();
+    final RestResponseEntityExceptionHandler exceptionHandler =
+            new RestResponseEntityExceptionHandler(mock(MessageTranslator.class), emptyList());
 
     @Test
     void handleConflict() {
@@ -46,20 +49,16 @@ class RestResponseEntityExceptionHandlerUnitTest {
     @Test
     void handleForeignKeyViolation() {
         // given
-        final var givenException = new DataIntegrityViolationException("""
-            ... violates foreign key constraint ...
-               Detail:   Second Line
-            Third Line
-            """);
+        final var givenException = new DataIntegrityViolationException("... violates foreign key constraint ...");
         final var givenWebRequest = mock(WebRequest.class);
 
         // when
         final var errorResponse = exceptionHandler.handleConflict(givenException, givenWebRequest);
 
         // then
-        assertThat(errorResponse.getBody().getStatusCode()).isEqualTo(400);
-        assertThat(errorResponse.getBody()).isNotNull()
-                .extracting(CustomErrorResponse::getMessage).isEqualTo("ERROR: [400] Second Line");
+        assertThat(errorResponse.getBody().getStatusCode()).isEqualTo(HttpStatus.CONFLICT.value());
+        assertThat(errorResponse.getBody()).isNotNull().extracting(CustomErrorResponse::getMessage).isEqualTo(
+                    "ERROR: [409] ... violates foreign key constraint ...");
     }
 
     @Test
@@ -127,24 +126,6 @@ class RestResponseEntityExceptionHandlerUnitTest {
         assertThat(errorResponse.getBody().getMessage()).isEqualTo("ERROR: [400] whatever error message");
     }
 
-    @Test
-    void handleJpaObjectRetrievalFailureExceptionWithEntityName() {
-        // given
-        final var givenException = new JpaObjectRetrievalFailureException(
-                new EntityNotFoundException("Unable to find "
-                        + NoDisplayNameEntity.class.getTypeName()
-                        + " with id 12345-123454")
-        );
-        final var givenWebRequest = mock(WebRequest.class);
-
-        // when
-        final var errorResponse = exceptionHandler.handleJpaObjectRetrievalFailureException(givenException, givenWebRequest);
-
-        // then
-        assertThat(errorResponse.getBody().getStatusCode()).isEqualTo(400);
-        assertThat(errorResponse.getBody().getMessage()).isEqualTo("ERROR: [400] Unable to find NoDisplayNameEntity with uuid 12345-123454");
-    }
-
     @Test
     void jpaExceptionWithUnknownErrorCode() {
         // given

src/test/java/net/hostsharing/hsadminng/hs/booking/item/HsBookingItemControllerAcceptanceTest.java

@@ -45,7 +45,7 @@ import static org.hamcrest.Matchers.matchesRegex;
 
 @SpringBootTest(
         webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
-        classes = { HsadminNgApplication.class, DisableSecurityConfig.class, JpaAttempt.class }
+        classes = { HsadminNgApplication.class, DisableSecurityConfig.class, JpaAttempt.class}
 )
 @ActiveProfiles("test")
 @Transactional

src/test/java/net/hostsharing/hsadminng/hs/booking/item/HsBookingItemControllerRestTest.java

@@ -1,6 +1,7 @@
 package net.hostsharing.hsadminng.hs.booking.item;
 
 import net.hostsharing.hsadminng.config.JsonObjectMapperConfiguration;
+import net.hostsharing.hsadminng.config.MessageTranslator;
 import net.hostsharing.hsadminng.context.Context;
 import net.hostsharing.hsadminng.hs.booking.generated.api.v1.model.HsBookingItemInsertResource;
 import net.hostsharing.hsadminng.hs.booking.project.HsBookingProjectRealEntity;
@@ -42,7 +43,7 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
 @WebMvcTest(HsBookingItemController.class)
-@Import({StrictMapper.class, JsonObjectMapperConfiguration.class, DisableSecurityConfig.class})
+@Import({StrictMapper.class, JsonObjectMapperConfiguration.class, DisableSecurityConfig.class, MessageTranslator.class})
 @RunWith(SpringRunner.class)
 @ActiveProfiles("test")
 class HsBookingItemControllerRestTest {

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/HsHostingAssetControllerRestTest.java

@@ -6,6 +6,7 @@ import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.SerializationFeature;
 import lombok.SneakyThrows;
 import net.hostsharing.hsadminng.config.JsonObjectMapperConfiguration;
+import net.hostsharing.hsadminng.config.MessageTranslator;
 import net.hostsharing.hsadminng.context.Context;
 import net.hostsharing.hsadminng.hs.booking.item.HsBookingItemRealRepository;
 import net.hostsharing.hsadminng.mapper.Array;
@@ -55,7 +56,7 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
 @WebMvcTest(HsHostingAssetController.class)
-@Import({ StrictMapper.class, JsonObjectMapperConfiguration.class, DisableSecurityConfig.class })
+@Import({ StrictMapper.class, JsonObjectMapperConfiguration.class, DisableSecurityConfig.class, MessageTranslator.class })
 @RunWith(SpringRunner.class)
 @ActiveProfiles("test")
 public class HsHostingAssetControllerRestTest {

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsCloudServerHostingAssetValidatorUnitTest.java

@@ -54,7 +54,7 @@ class HsCloudServerHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactlyInAnyOrder(
-                "'identifier' expected to match '^vm[0-9][0-9][0-9][0-9]$', but is 'xyz99'");
+                "'identifier' expected to match '^vm[0-9][0-9][0-9][0-9]$' but is 'xyz99'");
     }
 
     @Test

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsDomainDnsSetupHostingAssetValidatorUnitTest.java

@@ -121,7 +121,7 @@ class HsDomainDnsSetupHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactly(
-                "'identifier' expected to match '^\\Qexample.org|DNS\\E$', but is 'example.org'"
+                "'identifier' expected to match '^\\Qexample.org|DNS\\E$' but is 'example.org'"
         );
     }
 
@@ -203,7 +203,7 @@ class HsDomainDnsSetupHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactlyInAnyOrder(
-                "'DOMAIN_DNS_SETUP:example.org|DNS.config.TTL' is expected to be of type Integer, but is of type String",
+                "'DOMAIN_DNS_SETUP:example.org|DNS.config.TTL' is expected to be of type Integer but is of type String",
                 "'DOMAIN_DNS_SETUP:example.org|DNS.config.user-RR' is expected to match any of [(\\*\\.)?([a-zA-Z0-9\\._-]+|@)[ \t]+(([1-9][0-9]*[mMhHdDwW]?)+[ \t]+)?[iI][nN][ \t]+[a-zA-Z]+[ \t]+(([^;]+)|(\".*\")|(\\(.*\\)))[ \t]*(;.*)?, (\\*\\.)?([a-zA-Z0-9\\._-]+|@)[ \t]+[iI][nN][ \t]+(([1-9][0-9]*[mMhHdDwW]?)+[ \t]+)?[a-zA-Z]+[ \t]+(([^;]+)|(\".*\")|(\\(.*\\)))[ \t]*(;.*)?] but '@     1814400  IN  1814400 BAD1  TTL only allowed once' does not match any",
                 "'DOMAIN_DNS_SETUP:example.org|DNS.config.user-RR' is expected to match any of [(\\*\\.)?([a-zA-Z0-9\\._-]+|@)[ \t]+(([1-9][0-9]*[mMhHdDwW]?)+[ \t]+)?[iI][nN][ \t]+[a-zA-Z]+[ \t]+(([^;]+)|(\".*\")|(\\(.*\\)))[ \t]*(;.*)?, (\\*\\.)?([a-zA-Z0-9\\._-]+|@)[ \t]+[iI][nN][ \t]+(([1-9][0-9]*[mMhHdDwW]?)+[ \t]+)?[a-zA-Z]+[ \t]+(([^;]+)|(\".*\")|(\\(.*\\)))[ \t]*(;.*)?] but 'www                        BAD1  Record-Class missing / not enough columns' does not match any");
     }

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsDomainHttpSetupHostingAssetValidatorUnitTest.java

@@ -88,7 +88,7 @@ class HsDomainHttpSetupHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactly(
-                "'identifier' expected to match '^\\Qexample.org|HTTP\\E$', but is 'example.org'"
+                "'identifier' expected to match '^\\Qexample.org|HTTP\\E$' but is 'example.org'"
         );
     }
 
@@ -155,7 +155,7 @@ class HsDomainHttpSetupHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactlyInAnyOrder(
-                "'DOMAIN_HTTP_SETUP:example.org|HTTP.config.htdocsfallback' is expected to be of type Boolean, but is of type String",
+                "'DOMAIN_HTTP_SETUP:example.org|HTTP.config.htdocsfallback' is expected to be of type Boolean but is of type String",
                 "'DOMAIN_HTTP_SETUP:example.org|HTTP.config.fcgi-php-bin' is expected to match [^/.*] but 'false' does not match",
                 "'DOMAIN_HTTP_SETUP:example.org|HTTP.config.subdomains' is expected to match [(\\*|(?!-)[A-Za-z0-9-]{1,63}(?<!-))] but '' does not match",
                 "'DOMAIN_HTTP_SETUP:example.org|HTTP.config.subdomains' is expected to match [(\\*|(?!-)[A-Za-z0-9-]{1,63}(?<!-))] but '@' does not match",

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsDomainMboxHostingAssetValidatorUnitTest.java

@@ -63,7 +63,7 @@ class HsDomainMboxHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactly(
-                "'identifier' expected to match '^\\Qexample.org|MBOX\\E$', but is 'example.org'"
+                "'identifier' expected to match '^\\Qexample.org|MBOX\\E$' but is 'example.org'"
         );
     }
 

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsDomainSetupHostingAssetValidatorUnitTest.java

@@ -93,7 +93,7 @@ class HsDomainSetupHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).contains(
-                "'identifier' expected to match '(\\*|(?!-)[A-Za-z0-9-]{1,63}(?<!-))\\.example\\.org', but is '"
+                "'identifier' expected to match '(\\*|(?!-)[A-Za-z0-9-]{1,63}(?<!-))\\.example\\.org' but is '"
                         + testCase.domainName + "'"
         );
     }
@@ -179,7 +179,7 @@ class HsDomainSetupHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactlyInAnyOrder(
-                "'identifier' expected to match 'example.org', but is 'not-matching-booking-item-domain-name.org'");
+                "'identifier' expected to match 'example.org' but is 'not-matching-booking-item-domain-name.org'");
     }
 
     @ParameterizedTest
@@ -197,8 +197,8 @@ class HsDomainSetupHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactlyInAnyOrder(
-                "'identifier' expected to match '(\\*|(?!-)[A-Za-z0-9-]{1,63}(?<!-))\\.example\\.org', " +
-                        "but is '" + newDomainName + "'");
+                "'identifier' expected to match '(\\*|(?!-)[A-Za-z0-9-]{1,63}(?<!-))\\.example\\.org'" +
+                        " but is '" + newDomainName + "'");
     }
 
     @Test
@@ -490,7 +490,7 @@ class HsDomainSetupHostingAssetValidatorUnitTest {
 
         void isRejectedDueToInvalidIdentifier() {
             assertThat(validate()).contains(
-                    "'identifier' expected to match '(\\*|(?!-)[A-Za-z0-9-]{1,63}(?<!-))\\.example\\.net', but is 'sub.example.org'"
+                    "'identifier' expected to match '(\\*|(?!-)[A-Za-z0-9-]{1,63}(?<!-))\\.example\\.net' but is 'sub.example.org'"
             );
         }
 

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsDomainSmtpSetupHostingAssetValidatorUnitTest.java

@@ -64,7 +64,7 @@ class HsDomainSmtpSetupHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactly(
-                "'identifier' expected to match '^\\Qexample.org|SMTP\\E$', but is 'example.org'"
+                "'identifier' expected to match '^\\Qexample.org|SMTP\\E$' but is 'example.org'"
         );
     }
 

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsEMailAddressHostingAssetValidatorUnitTest.java

@@ -196,7 +196,7 @@ class HsEMailAddressHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactlyInAnyOrder(
-                "'identifier' expected to match '^\\Qold-local-part@example.org\\E$', but is 'abc00-office'");
+                "'identifier' expected to match '^\\Qold-local-part@example.org\\E$' but is 'abc00-office'");
     }
 
     @Test

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsEMailAliasHostingAssetValidatorUnitTest.java

@@ -119,7 +119,7 @@ class HsEMailAliasHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactlyInAnyOrder(
-                "'identifier' expected to match '^xyz00$|^xyz00-[a-z0-9][a-z0-9\\._-]*$', but is 'abc00-office'");
+                "'identifier' expected to match '^xyz00$|^xyz00-[a-z0-9][a-z0-9\\._-]*$' but is 'abc00-office'");
     }
 
     @Test

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsIPv4NumberHostingAssetValidatorUnitTest.java

@@ -60,7 +60,7 @@ class HsIPv4NumberHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactly(
-                "'identifier' expected to match '^((25[0-5]|(2[0-4]|1\\d|[1-9]|)\\d)\\.?\\b){4}$', but is '" + givenIdentifier + "'"
+                "'identifier' expected to match '^((25[0-5]|(2[0-4]|1\\d|[1-9]|)\\d)\\.?\\b){4}$' but is '" + givenIdentifier + "'"
         );
     }
 

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsIPv6NumberHostingAssetValidatorUnitTest.java

@@ -60,7 +60,7 @@ class HsIPv6NumberHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).contains(
-                "'identifier' expected to be a valid IPv6 address, but is '" + givenIdentifier + "'"
+                "'identifier' expected to be a valid IPv6 address but is '" + givenIdentifier + "'"
         );
     }
 

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsManagedServerHostingAssetValidatorUnitTest.java

@@ -43,7 +43,7 @@ class HsManagedServerHostingAssetValidatorUnitTest {
                 "'MANAGED_SERVER:vm1234.assignedToAsset' must be null but is of type CLOUD_SERVER",
                 "'MANAGED_SERVER:vm1234.config.monit_max_cpu_usage' is expected to be at least 10 but is 2",
                 "'MANAGED_SERVER:vm1234.config.monit_max_ram_usage' is expected to be at most 100 but is 101",
-                "'MANAGED_SERVER:vm1234.config.monit_max_hdd_usage' is expected to be of type Integer, but is of type String");
+                "'MANAGED_SERVER:vm1234.config.monit_max_hdd_usage' is expected to be of type Integer but is of type String");
     }
 
     @Test
@@ -61,7 +61,7 @@ class HsManagedServerHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactlyInAnyOrder(
-                "'identifier' expected to match '^vm[0-9][0-9][0-9][0-9]$', but is 'xyz00'");
+                "'identifier' expected to match '^vm[0-9][0-9][0-9][0-9]$' but is 'xyz00'");
     }
 
     @Test

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsManagedWebspaceHostingAssetValidatorUnitTest.java

@@ -101,7 +101,7 @@ class HsManagedWebspaceHostingAssetValidatorUnitTest {
         final var result = validator.validateEntity(mangedWebspaceHostingAssetEntity);
 
         // then
-        assertThat(result).containsExactly("'identifier' expected to match '^abc[0-9][0-9]$', but is 'xyz00'");
+        assertThat(result).containsExactly("'identifier' expected to match '^abc[0-9][0-9]$' but is 'xyz00'");
     }
 
     @Test

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsMariaDbDatabaseHostingAssetValidatorUnitTest.java

@@ -100,7 +100,7 @@ class HsMariaDbDatabaseHostingAssetValidatorUnitTest {
         // then
         assertThat(result).containsExactlyInAnyOrder(
                 "'MARIADB_DATABASE:MAD|xyz00_temp.config.unknown' is not expected but is set to 'wrong'",
-                "'MARIADB_DATABASE:MAD|xyz00_temp.config.encoding' is expected to be of type String, but is of type Integer"
+                "'MARIADB_DATABASE:MAD|xyz00_temp.config.encoding' is expected to be of type String but is of type Integer"
         );
     }
 
@@ -117,6 +117,6 @@ class HsMariaDbDatabaseHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactly(
-                "'identifier' expected to match '^MAD\\|xyz00$|^MAD\\|xyz00_[a-zA-Z0-9_]+$', but is 'xyz99-temp'");
+                "'identifier' expected to match '^MAD\\|xyz00$|^MAD\\|xyz00_[a-zA-Z0-9_]+$' but is 'xyz99-temp'");
     }
 }

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsMariaDbInstanceHostingAssetValidatorUnitTest.java

@@ -72,7 +72,7 @@ class HsMariaDbInstanceHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactly(
-                "'identifier' expected to match '^\\Qvm1234|MariaDB.default\\E$', but is 'example.org'"
+                "'identifier' expected to match '^\\Qvm1234|MariaDB.default\\E$' but is 'example.org'"
         );
     }
 

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsMariaDbUserHostingAssetValidatorUnitTest.java

@@ -128,6 +128,6 @@ class HsMariaDbUserHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactly(
-                "'identifier' expected to match '^MAU\\|xyz00$|^MAU\\|xyz00_[a-zA-Z0-9_]+$', but is 'xyz99-temp'");
+                "'identifier' expected to match '^MAU\\|xyz00$|^MAU\\|xyz00_[a-zA-Z0-9_]+$' but is 'xyz99-temp'");
     }
 }

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsPostgreSqlDatabaseHostingAssetValidatorUnitTest.java

@@ -123,7 +123,7 @@ class HsPostgreSqlDatabaseHostingAssetValidatorUnitTest {
         // then
         assertThat(result).containsExactlyInAnyOrder(
                 "'PGSQL_DATABASE:PGD|xyz00_db.config.unknown' is not expected but is set to 'wrong'",
-                "'PGSQL_DATABASE:PGD|xyz00_db.config.encoding' is expected to be of type String, but is of type Integer"
+                "'PGSQL_DATABASE:PGD|xyz00_db.config.encoding' is expected to be of type String but is of type Integer"
         );
     }
 
@@ -140,6 +140,6 @@ class HsPostgreSqlDatabaseHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactly(
-                "'identifier' expected to match '^PGD\\|xyz00$|^PGD\\|xyz00_[a-zA-Z0-9_]+$', but is 'xyz99-temp'");
+                "'identifier' expected to match '^PGD\\|xyz00$|^PGD\\|xyz00_[a-zA-Z0-9_]+$' but is 'xyz99-temp'");
     }
 }

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsPostgreSqlInstanceHostingAssetValidatorUnitTest.java

@@ -71,7 +71,7 @@ class HsPostgreSqlInstanceHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactly(
-                "'identifier' expected to match '^\\Qvm1234|PgSql.default\\E$', but is 'PostgreSQL'"
+                "'identifier' expected to match '^\\Qvm1234|PgSql.default\\E$' but is 'PostgreSQL'"
         );
     }
 

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsPostgreSqlUserHostingAssetValidatorUnitTest.java

@@ -126,6 +126,6 @@ class HsPostgreSqlUserHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactly(
-                "'identifier' expected to match '^PGU\\|xyz00$|^PGU\\|xyz00_[a-zA-Z0-9_]+$', but is 'xyz99-temp'");
+                "'identifier' expected to match '^PGU\\|xyz00$|^PGU\\|xyz00_[a-zA-Z0-9_]+$' but is 'xyz99-temp'");
     }
 }

src/test/java/net/hostsharing/hsadminng/hs/hosting/asset/validators/HsUnixUserHostingAssetValidatorUnitTest.java

@@ -162,7 +162,7 @@ class HsUnixUserHostingAssetValidatorUnitTest {
 
         // then
         assertThat(result).containsExactly(
-                "'identifier' expected to match '^abc00$|^abc00-[a-z0-9\\._-]+$', but is 'xyz99-temp'");
+                "'identifier' expected to match '^abc00$|^abc00-[a-z0-9\\._-]+$' but is 'xyz99-temp'");
     }
 
     @Test

src/test/java/net/hostsharing/hsadminng/hs/migration/ImportHostingAssets.java

@@ -1230,7 +1230,7 @@ public class ImportHostingAssets extends CsvDataImport {
                     final var free = rec.getBoolean("free");
 
                     assertThat(old_inet_addr_id)
-                            .as("packet.old_inet_addr_id not supported, but is not null for " + packet_name)
+                            .as("packet.old_inet_addr_id not supported but is not null for " + packet_name)
                             .isNull();
 
                     final var biType = determineBiType(basepacket_code);
@@ -1245,7 +1245,7 @@ public class ImportHostingAssets extends CsvDataImport {
 
                     logError(() -> assertThat(!free || haType == MANAGED_WEBSPACE || defaultPrefix(bookingItem)
                             .equals("hsh"))
-                            .as("packet.free only supported for Hostsharing-Assets and ManagedWebspace in customer-ManagedServer, but is set for "
+                            .as("packet.free only supported for Hostsharing-Assets and ManagedWebspace in customer-ManagedServerbut is set for "
                                     + packet_name)
                             .isTrue());
 
@@ -1739,7 +1739,7 @@ public class ImportHostingAssets extends CsvDataImport {
             return givenValue != null && !givenValue.isBlank() ? givenValue : defaultStringValue;
         }
         throw new RuntimeException(
-                "property default value expected to be of type string, but is of type " + defaultValue.getClass()
+                "property default value expected to be of type stringbut is of type " + defaultValue.getClass()
                         .getSimpleName());
     }
 

src/test/java/net/hostsharing/hsadminng/hs/migration/PostgresTestcontainer.java

@@ -64,7 +64,7 @@ public class PostgresTestcontainer {
     }
 
     private static void makeDir(final File dir) {
-        assertThat(!dir.exists() || dir.isDirectory()).describedAs(dir + " does exist, but is not a directory").isTrue();
+        assertThat(!dir.exists() || dir.isDirectory()).describedAs(dir + " does exist but is not a directory").isTrue();
         assertThat(dir.isDirectory() || dir.mkdirs()).describedAs(dir + " cannot be created").isTrue();
     }
 

src/test/java/net/hostsharing/hsadminng/hs/office/bankaccount/HsOfficeBankAccountControllerRestTest.java

@@ -1,5 +1,6 @@
 package net.hostsharing.hsadminng.hs.office.bankaccount;
 
+import net.hostsharing.hsadminng.config.MessageTranslator;
 import net.hostsharing.hsadminng.context.Context;
 import net.hostsharing.hsadminng.mapper.StrictMapper;
 import net.hostsharing.hsadminng.config.DisableSecurityConfig;
@@ -19,7 +20,7 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
 @WebMvcTest(HsOfficeBankAccountController.class)
-@Import(DisableSecurityConfig.class)
+@Import({DisableSecurityConfig.class, MessageTranslator.class})
 @ActiveProfiles("test")
 class HsOfficeBankAccountControllerRestTest {
 

src/test/java/net/hostsharing/hsadminng/hs/office/coopassets/HsOfficeCoopAssetsTransactionControllerAcceptanceTest.java

@@ -3,6 +3,7 @@ package net.hostsharing.hsadminng.hs.office.coopassets;
 import io.restassured.RestAssured;
 import io.restassured.http.ContentType;
 import net.hostsharing.hsadminng.HsadminNgApplication;
+import net.hostsharing.hsadminng.config.MessageTranslator;
 import net.hostsharing.hsadminng.context.Context;
 import net.hostsharing.hsadminng.hs.office.membership.HsOfficeMembershipRepository;
 import net.hostsharing.hsadminng.rbac.test.ContextBasedTestWithCleanup;
@@ -34,7 +35,8 @@ import static org.hamcrest.Matchers.startsWith;
 
 @SpringBootTest(
         webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
-        classes = { HsadminNgApplication.class, DisableSecurityConfig.class, JpaAttempt.class }
+        classes = { HsadminNgApplication.class, DisableSecurityConfig.class, JpaAttempt.class,
+                    MessageTranslator.class}
 )
 @ActiveProfiles("test")
 @Transactional
@@ -355,6 +357,7 @@ class HsOfficeCoopAssetsTransactionControllerAcceptanceTest extends ContextBased
             RestAssured // @formatter:off
                 .given()
                     .header("Authorization", "Bearer superuser-alex@hostsharing.net")
+                    .header("Accept-Language", "de")
                     .contentType(ContentType.JSON)
                     .body("""
                            {
@@ -376,7 +379,7 @@ class HsOfficeCoopAssetsTransactionControllerAcceptanceTest extends ContextBased
                             {
                                  "statusCode": 400,
                                  "statusPhrase": "Bad Request",
-                                 "message": "ERROR: [400] coop assets transaction would result in a negative balance of assets"
+                                 "message": "ERROR: [400] Geschäftsguthaben-Transaktion würde zu einem negativen Geschäftsguthaben-Saldo führen"
                              }
                         """));  // @formatter:on
         }

src/test/java/net/hostsharing/hsadminng/hs/office/coopassets/HsOfficeCoopAssetsTransactionControllerRestTest.java

@@ -1,10 +1,12 @@
 package net.hostsharing.hsadminng.hs.office.coopassets;
 
 import net.hostsharing.hsadminng.config.JsonObjectMapperConfiguration;
+import net.hostsharing.hsadminng.config.MessageTranslator;
 import net.hostsharing.hsadminng.context.Context;
 import net.hostsharing.hsadminng.hs.office.membership.HsOfficeMembershipEntity;
 import net.hostsharing.hsadminng.hs.office.membership.HsOfficeMembershipRepository;
 import net.hostsharing.hsadminng.hs.office.partner.HsOfficePartnerRealEntity;
+import net.hostsharing.hsadminng.config.MessagesResourceConfig;
 import net.hostsharing.hsadminng.mapper.StrictMapper;
 import net.hostsharing.hsadminng.persistence.EntityManagerWrapper;
 import net.hostsharing.hsadminng.rbac.test.JsonBuilder;
@@ -42,6 +44,7 @@ import static net.hostsharing.hsadminng.test.JsonMatcher.lenientlyEquals;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assumptions.assumeThat;
 import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.startsWith;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.when;
@@ -49,7 +52,11 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
 @WebMvcTest(HsOfficeCoopAssetsTransactionController.class)
-@Import({ StrictMapper.class, JsonObjectMapperConfiguration.class, DisableSecurityConfig.class })
+@Import({ StrictMapper.class,
+          MessagesResourceConfig.class,
+          MessageTranslator.class,
+          JsonObjectMapperConfiguration.class,
+          DisableSecurityConfig.class })
 @ActiveProfiles("test")
 @RunWith(SpringRunner.class)
 class HsOfficeCoopAssetsTransactionControllerRestTest {
@@ -531,11 +538,12 @@ class HsOfficeCoopAssetsTransactionControllerRestTest {
     enum BadRequestTestCases {
         MEMBERSHIP_UUID_MISSING(
                 requestBody -> requestBody.without("membership.uuid"),
-                "[membershipUuid must not be null but is \"null\"]"), // TODO.impl: should be membership.uuid, Spring validation-problem?
+                // TODO.impl: should be membership.uuid, but the Hibernate validator does not use the name from @JsonProperty
+                "[membershipUuid darf nicht null sein"), // bracket because it's from a list of violations
 
         MEMBERSHIP_UUID_NOT_FOUND_OR_NOT_ACCESSIBLE(
                 requestBody -> requestBody.with("membership.uuid", UNAVAILABLE_UUID),
-                "membership.uuid " + UNAVAILABLE_UUID + " not found"),
+                "membership.uuid \"" + UNAVAILABLE_UUID + "\" nicht gefunden"),
 
         MEMBERSHIP_UUID_AND_MEMBER_NUMBER_MUST_NOT_BE_GIVEN_BOTH(
                 requestBody -> requestBody
@@ -543,92 +551,92 @@ class HsOfficeCoopAssetsTransactionControllerRestTest {
                         .with("assetValue", "-128.00")
                         .with("adoptingMembership.uuid", UNAVAILABLE_UUID)
                         .with("adoptingMembership.memberNumber", UNAVAILABLE_MEMBER_NUMBER),
-                "either adoptingMembership.uuid or adoptingMembership.memberNumber can be given, not both"),
+                "entweder adoptingMembership.uuid oder adoptingMembership.memberNumber muss angegeben werden, nicht beide"),
 
         MEMBERSHIP_UUID_OR_MEMBER_NUMBER_MUST_BE_GIVEN(
                 requestBody -> requestBody
                         .with("transactionType", TRANSFER)
                         .with("assetValue", "-128.00"),
-                "either adoptingMembership.uuid or adoptingMembership.memberNumber must be given for transactionType=TRANSFER"),
+                "für transactionType=TRANSFER muss entweder adoptingMembership.uuid oder adoptingMembership.memberNumber angegeben werden"),
 
         REVERSAL_ASSET_TRANSACTION_REQUIRES_REVERTED_ASSET_TX_UUID(
                 requestBody -> requestBody
                             .with("transactionType", REVERSAL)
                             .with("assetValue", "-128.00"),
-                "REVERSAL asset transaction requires revertedAssetTx.uuid"),
+                "eine REVERSAL Geschäftsguthaben-Transaktion erfordert die Angabe einer revertedAssetTx.uuid"),
 
         REVERSAL_ASSET_TRANSACTION_REQUIRES_AVAILABLE_REVERTED_ASSET_TX_UUID(
                 requestBody -> requestBody
                         .with("transactionType", REVERSAL)
                         .with("assetValue", "-128.00")
                         .with("revertedAssetTx.uuid", UNAVAILABLE_UUID),
-                "revertedAssetTx.uuid " + UNAVAILABLE_UUID + " not found"),
+                "revertedAssetTx.uuid \"" + UNAVAILABLE_UUID + "\" nicht gefunden"),
 
         REVERSAL_ASSET_TRANSACTION_MUST_NEGATE_VALUE_OF_REVERTED_ASSET_TX(
                 requestBody -> requestBody
                         .with("transactionType", REVERSAL)
                         .with("assetValue", "128.00")
                         .with("revertedAssetTx.uuid", SOME_EXISTING_LOSS_ASSET_TX_UUID),
-                "given assetValue=128.00 but must be negative value from reverted asset tx: -64"),
+                "assetValue=128,00 muss dem negativen Wert des Wertes der stornierten Geschäftsguthaben-Transaktion entsprechen: -64,00"),
 
         TRANSACTION_TYPE_MISSING(
                 requestBody -> requestBody.without("transactionType"),
-                "[transactionType must not be null but is \"null\"]"),
+                "[transactionType darf nicht null sein"),
 
         VALUE_DATE_MISSING(
                 requestBody -> requestBody.without("valueDate"),
-                "[valueDate must not be null but is \"null\"]"),
+                "[valueDate darf nicht null sein"),
 
         ASSETS_VALUE_FOR_DEPOSIT_MUST_BE_POSITIVE(
                 requestBody -> requestBody
                         .with("transactionType", DEPOSIT)
                         .with("assetValue", -64.00),
-                "[for DEPOSIT, assetValue must be positive but is \"-64.00\"]"),
+                "[für transactionType=DEPOSIT, muss assetValue positiv sein, ist aber -64,00]"),
 
         ASSETS_VALUE_FOR_DISBURSAL_MUST_BE_NEGATIVE(
                 requestBody -> requestBody
                         .with("transactionType", DISBURSAL)
                         .with("assetValue", 64.00),
-                "[for DISBURSAL, assetValue must be negative but is \"64.00\"]"),
+                "[für transactionType=DISBURSAL, muss assetValue negativ sein, ist aber 64,00]"),
 
         ADOPTING_MEMBERSHIP_MUST_NOT_BE_THE_SAME(
                 requestBody -> requestBody
                         .with("transactionType", TRANSFER)
                         .with("assetValue", -64.00)
                         .with("adoptingMembership.uuid", ORIGIN_MEMBERSHIP_UUID),
-                "transferring and adopting membership must be different, but both are M-1111100"),
+                "übertragende und annehmende Mitgliedschaft müssen unterschiedlich sein, aber beide sind M-1111100"),
 
         ADOPTING_MEMBERSHIP_NUMBER_FOR_TRANSFER_MUST_BE_GIVEN_AND_AVAILABLE(
                 requestBody -> requestBody
                         .with("transactionType", TRANSFER)
                         .with("assetValue", -64.00)
                         .with("adoptingMembership.memberNumber", UNAVAILABLE_MEMBER_NUMBER),
-                "adoptingMembership.memberNumber='M-1234699' not found or not accessible"),
+                "adoptingMembership.memberNumber \"M-1234699\" nicht gefunden oder nicht zugänglich"),
 
         ADOPTING_MEMBERSHIP_UUID_FOR_TRANSFER_MUST_BE_GIVEN_AND_AVAILABLE(
                 requestBody -> requestBody
                         .with("transactionType", TRANSFER)
                         .with("assetValue", -64.00)
                         .with("adoptingMembership.uuid", UNAVAILABLE_UUID),
-                "adoptingMembership.uuid='" + UNAVAILABLE_UUID + "' not found or not accessible"),
+                "adoptingMembership.uuid \"" + UNAVAILABLE_UUID + "\" nicht gefunden oder nicht zugänglich"),
 
         ASSETS_VALUE_MUST_NOT_BE_NULL(
                 requestBody -> requestBody
                         .with("transactionType", REVERSAL)
                         .with("assetValue", 0.00),
-                "[assetValue must not be 0 but is \"0.00\"]"),
+                "[assetValue darf nicht 0 sein]"),
 
         REFERENCE_MISSING(
                 requestBody -> requestBody.without("reference"),
-                "[reference must not be null but is \"null\"]"),
+                "[reference darf nicht null sein"),
 
         REFERENCE_TOO_SHORT(
                 requestBody -> requestBody.with("reference", "12345"),
-                "[reference size must be between 6 and 48 but is \"12345\"]"),
+                "[reference Größe muss zwischen 6 und 48 sein"), // OpenAPI Spring templates uses @Size, but should use @Length
 
         REFERENCE_TOO_LONG(
                 requestBody -> requestBody.with("reference", "0123456789012345678901234567890123456789012345678"),
-                "[reference size must be between 6 and 48 but is \"0123456789012345678901234567890123456789012345678\"]");
+                "[reference Größe muss zwischen 6 und 48 sein"); // OpenAPI Spring templates uses @Size, but should use @Length
 
         private final Function<JsonBuilder, JsonBuilder> givenBodyTransformation;
         private final String expectedErrorMessage;
@@ -652,12 +660,13 @@ class HsOfficeCoopAssetsTransactionControllerRestTest {
         //  - set SINGLE_TEST_CASE_EXECUTION to true - see above
         //  - select the test case enum value you want to run
         assumeThat(!SINGLE_TEST_CASE_EXECUTION ||
-                testCase == BadRequestTestCases.ADOPTING_MEMBERSHIP_MUST_NOT_BE_THE_SAME).isTrue();
+                testCase == BadRequestTestCases.MEMBERSHIP_UUID_OR_MEMBER_NUMBER_MUST_BE_GIVEN).isTrue();
 
         // when
         mockMvc.perform(MockMvcRequestBuilders
                         .post("/api/hs/office/coopassetstransactions")
                         .header("Authorization", "Bearer superuser-alex@hostsharing.net")
+                        .header("Accept-Language", "de")
                         .contentType(MediaType.APPLICATION_JSON)
                         .content(testCase.givenRequestBody())
                         .accept(MediaType.APPLICATION_JSON))
@@ -665,7 +674,7 @@ class HsOfficeCoopAssetsTransactionControllerRestTest {
                 // then
                 .andExpect(jsonPath("statusCode", is(400)))
                 .andExpect(jsonPath("statusPhrase", is("Bad Request")))
-                .andExpect(jsonPath("message", is("ERROR: [400] " + testCase.expectedErrorMessage)))
+                .andExpect(jsonPath("message", startsWith("ERROR: [400] " + testCase.expectedErrorMessage)))
                 .andExpect(status().is4xxClientError());
     }
 
@@ -944,4 +953,5 @@ class HsOfficeCoopAssetsTransactionControllerRestTest {
     private String suffixOf(final String memberNumber) {
         return memberNumber.substring("M-".length() + 5);
     }
+
 }

src/test/java/net/hostsharing/hsadminng/hs/office/coopshares/HsOfficeCoopSharesTransactionControllerRestTest.java

@@ -1,5 +1,6 @@
 package net.hostsharing.hsadminng.hs.office.coopshares;
 
+import net.hostsharing.hsadminng.config.MessageTranslator;
 import net.hostsharing.hsadminng.context.Context;
 import net.hostsharing.hsadminng.hs.office.membership.HsOfficeMembershipRepository;
 import net.hostsharing.hsadminng.mapper.StrictMapper;
@@ -20,12 +21,13 @@ import java.util.UUID;
 import java.util.function.Function;
 
 import static net.hostsharing.hsadminng.rbac.test.JsonBuilder.jsonObject;
+import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.is;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
 @WebMvcTest(HsOfficeCoopSharesTransactionController.class)
-@Import(DisableSecurityConfig.class)
+@Import({DisableSecurityConfig.class, MessageTranslator.class})
 @ActiveProfiles("test")
 class HsOfficeCoopSharesTransactionControllerRestTest {
 
@@ -59,45 +61,45 @@ class HsOfficeCoopSharesTransactionControllerRestTest {
     enum BadRequestTestCases {
         MEMBERSHIP_UUID_MISSING(
                 requestBody -> requestBody.without("membership.uuid"),
-                "[membershipUuid must not be null but is \"null\"]"),
+                "membershipUuid must not be null"),
 
         TRANSACTION_TYPE_MISSING(
                 requestBody -> requestBody.without("transactionType"),
-                "[transactionType must not be null but is \"null\"]"),
+                "transactionType must not be null"),
 
         VALUE_DATE_MISSING(
                 requestBody -> requestBody.without("valueDate"),
-                "[valueDate must not be null but is \"null\"]"),
+                "valueDate must not be null"),
 
         SHARES_COUNT_FOR_SUBSCRIPTION_MUST_BE_POSITIVE(
                 requestBody -> requestBody
                         .with("transactionType", "SUBSCRIPTION")
                         .with("shareCount", -1),
-                "[for SUBSCRIPTION, shareCount must be positive but is \"-1\"]"),
+                "for SUBSCRIPTION, shareCount must be positive but is \"-1\""),
 
         SHARES_COUNT_FOR_CANCELLATION_MUST_BE_NEGATIVE(
                 requestBody -> requestBody
                         .with("transactionType", "CANCELLATION")
                         .with("shareCount", 1),
-                "[for CANCELLATION, shareCount must be negative but is \"1\"]"),
+                "for CANCELLATION, shareCount must be negative but is \"1\""),
 
         SHARES_COUNT_MUST_NOT_BE_NULL(
                 requestBody -> requestBody
                         .with("transactionType", "REVERSAL")
                         .with("shareCount", 0),
-                "[shareCount must not be 0 but is \"0\"]"),
+                "shareCount must not be 0 but is \"0\""),
 
         REFERENCE_MISSING(
                 requestBody -> requestBody.without("reference"),
-                "[reference must not be null but is \"null\"]"),
+                "reference must not be null"),
 
         REFERENCE_TOO_SHORT(
                 requestBody -> requestBody.with("reference", "12345"),
-                "[reference size must be between 6 and 48 but is \"12345\"]"),
+                "reference size must be between 6 and 48 but is \"12345\""),
 
         REFERENCE_TOO_LONG(
                 requestBody -> requestBody.with("reference", "0123456789012345678901234567890123456789012345678"),
-                "[reference size must be between 6 and 48 but is \"0123456789012345678901234567890123456789012345678\"]");
+                "reference size must be between 6 and 48 but is \"0123456789012345678901234567890123456789012345678\"");
 
         private final Function<JsonBuilder, JsonBuilder> givenBodyTransformation;
         private final String expectedErrorMessage;
@@ -130,7 +132,7 @@ class HsOfficeCoopSharesTransactionControllerRestTest {
                 .andExpect(status().is4xxClientError())
                 .andExpect(jsonPath("statusCode", is(400)))
                 .andExpect(jsonPath("statusPhrase", is("Bad Request")))
-                .andExpect(jsonPath("message", is("ERROR: [400] " + testCase.expectedErrorMessage)));
+                .andExpect(jsonPath("message", containsString(testCase.expectedErrorMessage)));
     }
 
 }

src/test/java/net/hostsharing/hsadminng/hs/office/membership/HsOfficeMembershipControllerRestTest.java

@@ -1,5 +1,6 @@
 package net.hostsharing.hsadminng.hs.office.membership;
 
+import net.hostsharing.hsadminng.config.MessageTranslator;
 import net.hostsharing.hsadminng.context.Context;
 import net.hostsharing.hsadminng.hs.office.coopassets.HsOfficeCoopAssetsTransactionRepository;
 import net.hostsharing.hsadminng.hs.office.partner.HsOfficePartnerRbacEntity;
@@ -30,13 +31,14 @@ import static net.hostsharing.hsadminng.test.JsonMatcher.lenientlyEquals;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.is;
+import static org.hamcrest.Matchers.startsWith;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.when;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
 @WebMvcTest(HsOfficeMembershipController.class)
-@Import({StrictMapper.class, DisableSecurityConfig.class})
+@Import({StrictMapper.class, DisableSecurityConfig.class, MessageTranslator.class})
 @ActiveProfiles("test")
 public class HsOfficeMembershipControllerRestTest {
 
@@ -74,6 +76,9 @@ public class HsOfficeMembershipControllerRestTest {
     @MockitoBean
     Context contextMock;
 
+    @Autowired
+    MessageTranslator messageTranslator;
+
     @MockitoBean
     HsOfficeCoopAssetsTransactionRepository coopAssetsTransactionRepo;
 
@@ -249,7 +254,7 @@ public class HsOfficeMembershipControllerRestTest {
                     .andExpect(jsonPath("statusCode", is(400)))
                     .andExpect(jsonPath("statusPhrase", is("Bad Request")))
                     // FYI: the brackets around the message are here because it's actually an array, in this case of size 1
-                    .andExpect(jsonPath("message", is("ERROR: [400] [partnerUuid must not be null but is \"null\"]")));
+                    .andExpect(jsonPath("message", startsWith("ERROR: [400] [partnerUuid must not be null")));
         }
 
         @Test
@@ -310,7 +315,7 @@ public class HsOfficeMembershipControllerRestTest {
         }
 
         public enum InvalidMemberSuffixVariants {
-            MISSING("", "[memberNumberSuffix must not be null but is \"null\"]"),
+            MISSING("", "[memberNumberSuffix must not be null"),
             TOO_SMALL("\"memberNumberSuffix\": \"9\",", "memberNumberSuffix must match \"[0-9]{2}\" but is \"9\""),
             TOO_LARGE("\"memberNumberSuffix\": \"100\",", "memberNumberSuffix must match \"[0-9]{2}\" but is \"100\""),
             NOT_NUMERIC("\"memberNumberSuffix\": \"AA\",", "memberNumberSuffix must match \"[0-9]{2}\" but is \"AA\""),

src/test/java/net/hostsharing/hsadminng/hs/office/partner/HsOfficePartnerControllerRestTest.java

@@ -1,5 +1,7 @@
 package net.hostsharing.hsadminng.hs.office.partner;
 
+import net.hostsharing.hsadminng.config.DisableSecurityConfig;
+import net.hostsharing.hsadminng.config.MessageTranslator;
 import net.hostsharing.hsadminng.context.Context;
 import net.hostsharing.hsadminng.hs.office.contact.HsOfficeContactFromResourceConverter;
 import net.hostsharing.hsadminng.hs.office.contact.HsOfficeContactRbacEntity;
@@ -8,17 +10,18 @@ import net.hostsharing.hsadminng.hs.office.relation.HsOfficeRelationRealEntity;
 import net.hostsharing.hsadminng.hs.office.relation.HsOfficeRelationRealRepository;
 import net.hostsharing.hsadminng.mapper.StrictMapper;
 import net.hostsharing.hsadminng.persistence.EntityManagerWrapper;
-import net.hostsharing.hsadminng.config.DisableSecurityConfig;
+import net.hostsharing.hsadminng.config.MessagesResourceConfig;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 import org.mockito.Mock;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
-import org.springframework.test.context.bean.override.mockito.MockitoBean;
+import org.springframework.context.MessageSource;
 import org.springframework.context.annotation.Import;
 import org.springframework.http.MediaType;
 import org.springframework.test.context.ActiveProfiles;
+import org.springframework.test.context.bean.override.mockito.MockitoBean;
 import org.springframework.test.web.servlet.MockMvc;
 import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
 
@@ -30,7 +33,7 @@ import java.util.Optional;
 import java.util.UUID;
 
 import static org.hamcrest.Matchers.is;
-import static org.hamcrest.Matchers.startsWith;
+import static org.hamcrest.Matchers.equalTo;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.lenient;
@@ -39,7 +42,11 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
 @WebMvcTest(HsOfficePartnerController.class)
-@Import({ StrictMapper.class, HsOfficeContactFromResourceConverter.class, DisableSecurityConfig.class})
+@Import({ StrictMapper.class,
+          MessagesResourceConfig.class,
+          MessageTranslator.class,
+          HsOfficeContactFromResourceConverter.class,
+          DisableSecurityConfig.class })
 @ActiveProfiles("test")
 class HsOfficePartnerControllerRestTest {
 
@@ -54,6 +61,12 @@ class HsOfficePartnerControllerRestTest {
     @MockitoBean
     Context contextMock;
 
+    @Autowired
+    MessageSource messageSource;
+
+    @Autowired
+    MessageTranslator translator;
+
     @MockitoBean
     HsOfficePartnerRbacRepository partnerRepo;
 
@@ -100,6 +113,7 @@ class HsOfficePartnerControllerRestTest {
             mockMvc.perform(MockMvcRequestBuilders
                             .post("/api/hs/office/partners")
                             .header("Authorization", "Bearer superuser-alex@hostsharing.net")
+                            .header("Accept-Language", "de")
                             .contentType(MediaType.APPLICATION_JSON)
                             .content("""
                                      {
@@ -124,7 +138,8 @@ class HsOfficePartnerControllerRestTest {
                     .andExpect(status().is4xxClientError())
                     .andExpect(jsonPath("statusCode", is(400)))
                     .andExpect(jsonPath("statusPhrase", is("Bad Request")))
-                    .andExpect(jsonPath("message", startsWith("ERROR: [400] Cannot resolve HsOfficePersonRealEntity with uuid ")));
+                    .andExpect(jsonPath("message", equalTo(
+                            "ERROR: [400] RealPerson \"00000000-0000-0000-0000-000000000000\" nicht gefunden")));
         }
 
         @Test
@@ -157,7 +172,8 @@ class HsOfficePartnerControllerRestTest {
                     .andExpect(status().is4xxClientError())
                     .andExpect(jsonPath("statusCode", is(400)))
                     .andExpect(jsonPath("statusPhrase", is("Bad Request")))
-                    .andExpect(jsonPath("message", startsWith("ERROR: [400] Cannot resolve HsOfficeContactRealEntity with uuid ")));
+                    .andExpect(jsonPath("message", equalTo(
+                            "ERROR: [400] RealContact \"00000000-0000-0000-0000-000000000000\" not found")));
         }
     }
 
@@ -173,14 +189,14 @@ class HsOfficePartnerControllerRestTest {
 
             // when
             mockMvc.perform(MockMvcRequestBuilders
-                    .get("/api/hs/office/partners/P-12345")
-                    .header("Authorization", "Bearer superuser-alex@hostsharing.net")
-                    .contentType(MediaType.APPLICATION_JSON)
-                    .accept(MediaType.APPLICATION_JSON))
+                            .get("/api/hs/office/partners/P-12345")
+                            .header("Authorization", "Bearer superuser-alex@hostsharing.net")
+                            .contentType(MediaType.APPLICATION_JSON)
+                            .accept(MediaType.APPLICATION_JSON))
 
-            // then
-            .andExpect(status().isOk())
-            .andExpect(jsonPath("partnerNumber", is("P-12345")));
+                    // then
+                    .andExpect(status().isOk())
+                    .andExpect(jsonPath("partnerNumber", is("P-12345")));
         }
 
         @Test
@@ -190,13 +206,13 @@ class HsOfficePartnerControllerRestTest {
 
             // when
             mockMvc.perform(MockMvcRequestBuilders
-                    .get("/api/hs/office/partners/P-12345")
-                    .header("Authorization", "Bearer superuser-alex@hostsharing.net")
-                    .contentType(MediaType.APPLICATION_JSON)
-                    .accept(MediaType.APPLICATION_JSON))
+                            .get("/api/hs/office/partners/P-12345")
+                            .header("Authorization", "Bearer superuser-alex@hostsharing.net")
+                            .contentType(MediaType.APPLICATION_JSON)
+                            .accept(MediaType.APPLICATION_JSON))
 
-            // then
-            .andExpect(status().isNotFound());
+                    // then
+                    .andExpect(status().isNotFound());
         }
     }
 

src/test/java/net/hostsharing/hsadminng/hs/office/scenarios/HsOfficeScenarioTests.java

@@ -273,7 +273,7 @@ class HsOfficeScenarioTests extends ScenarioTest {
         void shouldCreateSelfDebitorForPartnerWithIdenticalContactData() {
             new CreateSelfDebitorForPartnerWithIdenticalContactData(scenarioTest)
                     .given("partnerNumber", "P-31011")
-                    .given("debitorNumberSuffix", "00") // TODO.impl: could be assigned automatically, but is not yet
+                    .given("debitorNumberSuffix", "00") // TODO.impl: could be assigned automatically but is not yet
                     .given("billable", true)
                     .given("vatBusiness", false)
                     .given("vatReverseCharge", false)
@@ -291,7 +291,7 @@ class HsOfficeScenarioTests extends ScenarioTest {
                     .given("partnerPersonTradeName", "Test AG")
                     .given("billingContactCaption", "Test AG - billing department")
                     .given("billingContactEmailAddress", "billing@test-ag.example.org")
-                    .given("debitorNumberSuffix", "00") // TODO.impl: could be assigned automatically, but is not yet
+                    .given("debitorNumberSuffix", "00") // TODO.impl: could be assigned automaticallybut is not yet
                     .given("billable", true)
                     .given("vatId", "VAT123456")
                     .given("vatCountryCode", "DE")

src/test/java/net/hostsharing/hsadminng/ping/PingControllerAcceptanceTest.java

@@ -0,0 +1,75 @@
+package net.hostsharing.hsadminng.ping;
+
+import io.restassured.RestAssured;
+import net.hostsharing.hsadminng.HsadminNgApplication;
+import net.hostsharing.hsadminng.config.DisableSecurityConfig;
+import net.hostsharing.hsadminng.context.Context;
+import net.hostsharing.hsadminng.rbac.test.JpaAttempt;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.web.server.LocalServerPort;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.Locale;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@SpringBootTest(
+        webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT,
+        classes = {
+                HsadminNgApplication.class,
+                DisableSecurityConfig.class,
+                JpaAttempt.class
+        }
+)
+@ActiveProfiles("test")
+@Transactional
+@Tag("generalIntegrationTest")
+class PingControllerAcceptanceTest {
+
+    @LocalServerPort
+    private Integer port;
+
+    @Autowired
+    Context context;
+
+    @Autowired
+    Context contextMock;
+
+    enum PingTranslationTestCase {
+        EN(Locale.ENGLISH, "pong superuser-alex@hostsharing.net - in English"),
+        DE(Locale.GERMAN, "pong superuser-alex@hostsharing.net - auf Deutsch"),
+        FR(Locale.FRENCH, "pong superuser-alex@hostsharing.net - in English [fr translation missing]");
+
+        Locale givenLocale;
+        CharSequence expectedPongTranslation;
+
+        PingTranslationTestCase(final Locale givenLocale, final String expectedPongTranslation) {
+            this.givenLocale = givenLocale;
+            this.expectedPongTranslation = expectedPongTranslation;
+        }
+    }
+
+    @ParameterizedTest
+    @EnumSource(PingTranslationTestCase.class)
+    void pingRepliesWithTranslatedPongResponse(final PingTranslationTestCase testCase) {
+        final var responseBody = RestAssured // @formatter:off
+                .given()
+                    .header("Authorization", "Bearer superuser-alex@hostsharing.net")
+                    .header("Accept-Language", testCase.givenLocale)
+                    .port(port)
+                .when()
+                    .get("http://localhost/api/ping")
+                .then().log().all().assertThat()
+                    .statusCode(200)
+                    .contentType("text/plain;charset=UTF-8")
+                    .extract().body().asString();
+                // @formatter:on
+
+        assertThat(responseBody).isEqualTo(testCase.expectedPongTranslation + "\n");
+    }
+}

src/test/java/net/hostsharing/hsadminng/ping/PingControllerRestTest.java

@@ -0,0 +1,67 @@
+package net.hostsharing.hsadminng.ping;
+
+import lombok.RequiredArgsConstructor;
+import net.hostsharing.hsadminng.config.DisableSecurityConfig;
+import net.hostsharing.hsadminng.config.JsonObjectMapperConfiguration;
+import net.hostsharing.hsadminng.config.MessageTranslator;
+import net.hostsharing.hsadminng.config.MessagesResourceConfig;
+import net.hostsharing.hsadminng.context.Context;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.context.annotation.Import;
+import org.springframework.http.MediaType;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.test.context.bean.override.mockito.MockitoBean;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
+
+import static org.hamcrest.Matchers.startsWith;
+import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+@WebMvcTest(PingController.class)
+@Import({ MessagesResourceConfig.class,
+          MessageTranslator.class,
+          JsonObjectMapperConfiguration.class,
+          DisableSecurityConfig.class })
+@RunWith(SpringRunner.class)
+@ActiveProfiles("test")
+class PingControllerRestTest {
+
+    @Autowired
+    MockMvc mockMvc;
+
+    @MockitoBean
+    Context contextMock;
+
+    @RequiredArgsConstructor
+    enum I18nTestCases {
+        EN("en", "pong anonymousUser - in English"),
+        DE("de", "pong anonymousUser - auf Deutsch");
+
+        final String language;
+        final String expectedTranslation;
+    }
+
+    @ParameterizedTest
+    @EnumSource(I18nTestCases.class)
+    void pingReturnsPongInEnglish(final I18nTestCases testCase) throws Exception {
+
+        // when
+        final var request = mockMvc.perform(MockMvcRequestBuilders
+                        .get("/api/ping")
+                        .header("Accept-Language", testCase.language)
+                        .accept(MediaType.TEXT_PLAIN))
+                .andDo(print());
+
+        // then
+        request
+            .andExpect(status().isOk())
+            .andExpect(content().string(startsWith(testCase.expectedTranslation)));
+    }
+}

src/test/java/net/hostsharing/hsadminng/rbac/role/RbacRoleControllerRestTest.java

@@ -1,5 +1,6 @@
 package net.hostsharing.hsadminng.rbac.role;
 
+import net.hostsharing.hsadminng.config.MessageTranslator;
 import net.hostsharing.hsadminng.context.Context;
 import net.hostsharing.hsadminng.mapper.StrictMapper;
 import net.hostsharing.hsadminng.persistence.EntityManagerWrapper;
@@ -31,7 +32,7 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
 @WebMvcTest(RbacRoleController.class)
-@Import({StrictMapper.class, DisableSecurityConfig.class})
+@Import({StrictMapper.class, DisableSecurityConfig.class, MessageTranslator.class})
 @ActiveProfiles("test")
 @RunWith(SpringRunner.class)
 class RbacRoleControllerRestTest {

src/test/java/net/hostsharing/hsadminng/rbac/subject/RbacSubjectControllerRestTest.java

@@ -1,5 +1,6 @@
 package net.hostsharing.hsadminng.rbac.subject;
 
+import net.hostsharing.hsadminng.config.MessageTranslator;
 import net.hostsharing.hsadminng.context.Context;
 import net.hostsharing.hsadminng.mapper.StrictMapper;
 import net.hostsharing.hsadminng.persistence.EntityManagerWrapper;
@@ -27,7 +28,7 @@ import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
 @WebMvcTest(RbacSubjectController.class)
-@Import({StrictMapper.class, DisableSecurityConfig.class})
+@Import({StrictMapper.class, DisableSecurityConfig.class, MessageTranslator.class})
 @ActiveProfiles("test")
 @RunWith(SpringRunner.class)
 class RbacSubjectControllerRestTest {