fixed entity-id format in built DittoHeaders of AcknowledgementAggreg…

…atorActor on timeout exceptions

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

internal/models/acks/src/main/java/org/eclipse/ditto/internal/models/acks/AcknowledgementAggregatorActor.java

@@ -127,7 +127,7 @@ private static DittoHeaders calculateHeadersWithEntityId(@Nullable final EntityI
         if (null != entityId) {
             return withDittoHeaders.getDittoHeaders()
                     .toBuilder()
-                    .putHeader(DittoHeaderDefinition.ENTITY_ID.getKey(), entityId.toString())
+                    .putHeader(DittoHeaderDefinition.ENTITY_ID.getKey(), entityId.getEntityType() + ":" + entityId)
                     .build();
         } else {
             return withDittoHeaders.getDittoHeaders();