title: JobExplorer.findRunningJobExecutions does not work correctly
body: <p>In a project I use spring-batch, as a part of cleanup for processes that stuck I use 
  <code>JobExplorer.findRunningJobExecutions(...)</code> 
  but that function return empty set. After digging I found next problem: spring-batch use SQL like 
  <code>SELECT E.JOB_EXECUTION_ID, ... from %PREFIX%JOB_EXECUTION E ... WHERE ... E.END_TIME is NULL ...</code>. After running long job, I got that from beginning 3 Dates in %PREFIX%JOB_EXECUTION (CREATE_TIME, START_TIME, END_TIME) have same value. This mean that SQL will always return empty set.</p>
  
  <p>Question is, am I one who get this?
  How to report bug to Spring team?   </p>