unwrap throwable exception

Author: hu-ahmed

internal/utils/persistent-actors/src/main/java/org/eclipse/ditto/internal/utils/persistentactors/AbstractPersistenceActor.java

@@ -817,7 +817,7 @@ public void onStagedQuery(final Command<?> command, final CompletionStage<WithDi
         if (command.getDittoHeaders().isResponseRequired()) {
             final ActorRef sender = getSender();
             response.whenComplete((r, throwable) -> {
-                if (throwable instanceof DittoRuntimeException dittoRuntimeException) {
+                if (unwrapThrowable(throwable) instanceof DittoRuntimeException dittoRuntimeException) {
                     notifySender(sender, dittoRuntimeException);
                 } else {
                     notifySender(sender, r);
@@ -840,6 +840,21 @@ public void onError(final DittoRuntimeException error, final Command<?> errorCau
         }
     }
 
+    /**
+     * Unwraps the root cause of the given {@link Throwable} if it is wrapped inside a {@link CompletionException}.
+     *
+     * @param throwable The throwable to unwrap.
+     * @return The unwrapped cause if the throwable is a {@link CompletionException} and has a cause,
+     *         otherwise returns the original throwable.
+     */
+    protected static Throwable unwrapThrowable(final Throwable throwable) {
+        if (throwable != null && throwable instanceof CompletionException) {
+            return throwable.getCause() != null ? throwable.getCause() : throwable;
+        }
+        return throwable;
+    }
+
+
     /**
      * Send a reply and increment access counter.
      *

things/service/src/main/java/org/eclipse/ditto/things/service/persistence/actors/ThingPersistenceActor.java

@@ -153,7 +153,7 @@ public void onStagedQuery(final Command<?> command, final CompletionStage<WithDi
             @Nullable final StartedSpan startedSpan) {
         final ActorRef sender = getSender();
         response.whenComplete((r, throwable) -> {
-            if (throwable instanceof DittoRuntimeException dittoRuntimeException) {
+            if (unwrapThrowable(throwable) instanceof DittoRuntimeException dittoRuntimeException) {
                 notifySender(sender, dittoRuntimeException);
             } else {
                 doOnQuery(command, r, sender);