Description of problem:

When a request to kie-server is performed two Marhalling operations are done: one for "result" and a second for the rest of the payload with container information.

In a JSON respose, the first marshalling is added to the second as regular String, so when the second marshalling happens it adds additional quotes and escape characters to the result, due that a parse can not be done directly in client side.

Version-Release number of selected component (if applicable):
6.2

How reproducible:
Always

Steps to Reproduce:

- send to kie-server a json request to fire-all-rules including any fact with an "out-identifier", to make sure that a result will be sent back in the response containing that fact handle. 

Actual results:
- The result is returned in the response inside a String instead of a valid JSON format. That happens due the double marshalling. 

Expected results:
- the response should return a valid json format for "result" instead of a String.