Description of problem:

Designer doesn't save Meessage event attribute "MessageRef" in swime lan

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

How reproducible:

Steps to Reproduce:
1. create process
2. add lane
3. added start evet, script and messageEvent (throw intermediate event) and end event

4. set all require attribute for all event and activiy
5. add valeu for the attribute messafeRef in message event
6. save the process and close
7. open the process again and you wouldn't see the messageRef attribute value n

Actual results: validation error

, you get an error "
unable to parse xml : Exception class java.lang.IllegalArgumentException : No messages found

Expected results: Shouldn't gey error. all event and activity should be save with any error.

Additional info: