introduce HostingAssetEntitySaveProcessor.save using the EntityManager

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

@@ -79,7 +79,7 @@ public class HsHostingAssetController implements HsHostingAssetsApi {
                 .preprocessEntity()
                 .validateEntity()
                 .prepareForSave()
-                .saveUsing(rbacAssetRepo::save)
+                .save()
                 .validateContext()
                 .mapUsing(e -> mapper.map(e, HsHostingAssetResource.class))
                 .revampProperties();
@@ -140,7 +140,7 @@ public class HsHostingAssetController implements HsHostingAssetsApi {
                 .preprocessEntity()
                 .validateEntity()
                 .prepareForSave()
-                .saveUsing(rbacAssetRepo::save)
+                .save()
                 .validateContext()
                 .mapUsing(e -> mapper.map(e, HsHostingAssetResource.class))
                 .revampProperties();

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

@@ -58,19 +58,42 @@ public class HostingAssetEntitySaveProcessor {
     /// hashing passwords etc.
     @SuppressWarnings("unchecked")
     public HostingAssetEntitySaveProcessor prepareForSave() {
-        step("prepareForSave", "saveUsing");
+        step("prepareForSave", "save");
         validator.prepareProperties(em, entity);
         return this;
     }
 
+    /**
+     * Saves the entity using the given `saveFunction`.
+     *
+     * <p>`validator.postPersist(em, entity)` is NOT called.
+     * If any postprocessing is necessary, the saveFunction has to implement this.</p>
+     * @param saveFunction
+     * @return
+     */
     public HostingAssetEntitySaveProcessor saveUsing(final Function<HsHostingAsset, HsHostingAsset> saveFunction) {
-        step("saveUsing", "validateContext");
+        step("save", "validateContext");
         entity = saveFunction.apply(entity);
-        em.flush(); // makes RbacEntity available as RealEntity if needed
-        validator.postPersist(em, entity);
         return this;
     }
 
+    /**
+     * Saves the using the `EntityManager`, but does NOT ever merge the entity.
+     *
+     * <p>`validator.postPersist(em, entity)` is called afterwards with the entity guaranteed to be flushed to the database.</p>
+     * @return
+     */
+    public HostingAssetEntitySaveProcessor save() {
+        return saveUsing(e -> {
+            if (!em.contains(entity)) {
+                em.persist(entity);
+            }
+            em.flush(); // makes RbacEntity available as RealEntity if needed
+            validator.postPersist(em, entity);
+            return entity;
+        });
+    }
+
     /// validates the entity within it's parent and child hierarchy (e.g. totals validators and other limits)
     public HostingAssetEntitySaveProcessor validateContext() {
         step("validateContext", "mapUsing");

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

@@ -43,7 +43,7 @@ class HsManagedWebspaceHostingAssetValidator extends HostingAssetEntityValidator
                     .preprocessEntity()
                     .validateEntity()
                     .prepareForSave()
-                    .saveUsing(emw::persist)
+                    .save()
                     .validateContext();
             webspaceAsset.getConfig().put("groupid", unixUserAsset.getConfig().get("userid"));
         }