stip "lastModified" timestamp from QueryThingResponses (which was onl…

…y required for new search cutover and was filtered away in old concierge)

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

gateway/service/src/main/java/org/eclipse/ditto/gateway/service/proxy/actors/QueryThingsPerRequestActor.java

@@ -123,7 +123,7 @@ public Receive createReceive() {
                         // shortcuts: we don't have to look up the things
                         // - for no search results
                         // - if only the "thingId" was selected in the QueryThings commands
-                        originatingSender.tell(qtr, getSelf());
+                        originatingSender.tell(stripLastModifiedTimestampFromSearchResult(qtr), getSelf());
                         stopMyself();
                     } else {
                         final Optional<JsonFieldSelector> selectedFieldsWithThingId = getSelectedFieldsWithThingId();
@@ -166,6 +166,15 @@ public Receive createReceive() {
                 .build();
     }
 
+    private static QueryThingsResponse stripLastModifiedTimestampFromSearchResult(
+            final QueryThingsResponse queryThingsResponse) {
+
+        return queryThingsResponse.setEntity(queryThingsResponse.getSearchResult().toBuilder()
+                .lastModified(null)
+                .build()
+                .toJson());
+    }
+
     private boolean queryThingsOnlyContainsThingIdSelector() {
         final Optional<JsonFieldSelector> fields = queryThings.getFields();
         return fields.isPresent() && fields.get().getPointers()