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

@@ -8,7 +8,11 @@ import static java.lang.String.join;
 public class MultiValidationException extends ValidationException {
 
     private MultiValidationException(final List<String> violations) {
-        super("[\n" + join(",\n", violations) + "\n]");
+        super(
+                violations.size() > 1
+                    ? "[\n" + join(",\n", violations) + "\n]"
+                    : "[" + join(",\n", violations) + "]"
+        );
     }
 
     public static void throwInvalid(final List<String> violations) {

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

@@ -1,5 +1,6 @@
 package net.hostsharing.hsadminng.hs.hosting.asset;
 
+import net.hostsharing.hsadminng.hs.booking.item.HsBookingItemRepository;
 import net.hostsharing.hsadminng.hs.hosting.generated.api.v1.api.HsHostingAssetsApi;
 
 import net.hostsharing.hsadminng.context.Context;
@@ -34,6 +35,9 @@ public class HsHostingAssetController implements HsHostingAssetsApi {
     @Autowired
     private HsHostingAssetRepository assetRepo;
 
+    @Autowired
+    private HsBookingItemRepository bookingItemRepo;
+
     @Override
     @Transactional(readOnly = true)
     public ResponseEntity<List<HsHostingAssetResource>> listAssets(
@@ -124,6 +128,11 @@ public class HsHostingAssetController implements HsHostingAssetsApi {
 
     final BiConsumer<HsHostingAssetInsertResource, HsHostingAssetEntity> RESOURCE_TO_ENTITY_POSTMAPPER = (resource, entity) -> {
         entity.putConfig(KeyValueMap.from(resource.getConfig()));
+        if (resource.getBookingItemUuid() != null) {
+            entity.setBookingItem(bookingItemRepo.findByUuid(resource.getBookingItemUuid())
+                    .orElseThrow(() -> new EntityNotFoundException("ERROR: [400] bookingItemUuid %s not found".formatted(
+                            resource.getBookingItemUuid()))));
+        }
         if (resource.getParentAssetUuid() != null) {
             entity.setParentAsset(assetRepo.findByUuid(resource.getParentAssetUuid())
                     .orElseThrow(() -> new EntityNotFoundException("ERROR: [400] parentAssetUuid %s not found".formatted(

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

@@ -27,6 +27,7 @@ import jakarta.persistence.Id;
 import jakarta.persistence.JoinColumn;
 import jakarta.persistence.ManyToOne;
 import jakarta.persistence.OneToMany;
+import jakarta.persistence.OneToOne;
 import jakarta.persistence.Table;
 import jakarta.persistence.Transient;
 import jakarta.persistence.Version;
@@ -78,7 +79,7 @@ public class HsHostingAssetEntity implements Stringifyable, RbacObject {
     @Version
     private int version;
 
-    @ManyToOne(fetch = FetchType.LAZY)
+    @OneToOne(fetch = FetchType.LAZY)
     @JoinColumn(name = "bookingitemuuid")
     private HsBookingItemEntity bookingItem;
 

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

@@ -332,9 +332,7 @@ class HsHostingAssetControllerAcceptanceTest extends ContextBasedTestWithCleanup
                         .body("", lenientlyEquals("""
                                     {
                                         "statusPhrase": "Bad Request",
-                                        "message": "[
-                                                 <<<'D-1000111:D-1000111 default project:separate ManagedWebspace.resources.Multi=1 allows at maximum 25 unix users, but 26 found
-                                                 <<<]"
+                                        "message": "['D-1000111:D-1000111 default project:separate ManagedWebspace.resources.Multi=1 allows at maximum 25 unix users, but 26 found]"
                                     }
                                     """.replaceAll(" +<<<", "")));  // @formatter:on
         }

src/test/java/net/hostsharing/hsadminng/hs/office/debitor/HsOfficeDebitorRepositoryIntegrationTest.java

@@ -109,9 +109,9 @@ class HsOfficeDebitorRepositoryIntegrationTest extends ContextBasedTestWithClean
             assertThat(debitorRepo.count()).isEqualTo(count + 1);
         }
 
+        @Transactional
         @ParameterizedTest
         @ValueSource(strings = {"", "a", "ab", "a12", "123", "12a"})
-        @Transactional
         public void canNotCreateNewDebitorWithInvalidDefaultPrefix(final String givenPrefix) {
             // given
             context("superuser-alex@hostsharing.net");

src/test/java/net/hostsharing/hsadminng/rbac/test/ContextBasedTestWithCleanup.java

@@ -14,6 +14,7 @@ import org.junit.jupiter.api.TestInfo;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.Repository;
+import org.springframework.transaction.PlatformTransactionManager;
 
 import jakarta.persistence.*;
 import java.util.*;
@@ -28,9 +29,13 @@ import static org.assertj.core.api.Assertions.assertThat;
 public abstract class ContextBasedTestWithCleanup extends ContextBasedTest {
 
     private static final boolean DETAILED_BUT_SLOW_CHECK = true;
+
     @PersistenceContext
     protected EntityManager em;
 
+    @Autowired
+    private PlatformTransactionManager tm;
+
     @Autowired
     RbacGrantRepository rbacGrantRepo;
 
@@ -166,13 +171,17 @@ public abstract class ContextBasedTestWithCleanup extends ContextBasedTest {
 
     @AfterEach
     void cleanupAndCheckCleanup(final TestInfo testInfo) {
+        // If the whole test method has its own transaction, cleanup makes no sense.
+        // If that transaction even failed, cleaunup would cause an exception.
+        if (!tm.getTransaction(null).isRollbackOnly()) {
             out.println(ContextBasedTestWithCleanup.class.getSimpleName() + ".cleanupAndCheckCleanup");
             cleanupTemporaryTestData();
             deleteLeakedRbacObjects();
-        long rbacObjectCount = assertNoNewRbacObjectsRolesAndGrantsLeaked();
 
+            long rbacObjectCount = assertNoNewRbacObjectsRolesAndGrantsLeaked();
             out.println("TOTAL OBJECT COUNT (after): " + rbacObjectCount);
         }
+    }
 
     private void cleanupTemporaryTestData() {
         // For better performance in a single transaction ...