Created two patch to fix this issue:
1) the patch with timestamp: when ATS generates the Application create_time, it would read ApplicationMetricsConstants.SUBMITTED_TIME_ENTITY_INFO instead of timelineevent timestamp
2) the patch without timestamp: when create RMAppImpl object, we would use startTime as an input. If this is the new Application, the startTime would be set as currentTimeStamp. If it is the recovered application, the startTime would be set from appState. By doing this, we could also get the consistent application start time from both RM Web ui and ATS ui.
Personally, I prefer the option 2.
Jason Lowe, Naganarasimha G R, Jonathan Eagles what does you think ?