fix pitest, spotless and cleanup

build.gradle

@@ -182,7 +182,7 @@ openApiGenerate.dependsOn processSpring
 // Spotless Code Formatting
 spotless {
     java {
-        // removeUnusedImports() TODO: reactivate once it can deal with multi-line-strings
+        removeUnusedImports()
         indentWithSpaces(4)
         endWithNewline()
         toggleOffOn()
@@ -193,8 +193,14 @@ spotless {
         }
     }
 }
-project.tasks.spotlessJava.dependsOn(tasks.generateLicenseReport, tasks.processResources, tasks.processTestResources)
 project.tasks.check.dependsOn(spotlessCheck)
+// HACK: no idea why spotless uses the output of these tasks, but we get warnings without those
+project.tasks.spotlessJava.dependsOn(
+        tasks.generateLicenseReport,
+        tasks.pitest,
+        tasks.jacocoTestReport,
+        tasks.processResources,
+        tasks.processTestResources)
 
 // OWASP Dependency Security Test
 dependencyCheck {
@@ -302,7 +308,7 @@ pitest {
     targetTests = ['net.hostsharing.hsadminng.**.*UnitTest', 'net.hostsharing.hsadminng.**.*RestTest']
     excludedTestClasses = ['**AcceptanceTest*', '**IntegrationTest*']
 
-    pitestVersion = '1.9.9'
+    pitestVersion = '1.15.3'
     junit5PluginVersion = '1.1.0'
 
     threads = 4