MULE-7265: Stop already started message processors if one of the flow processors fails to start up. This keeps the phases of the flow and its processors in a consistent state.
MULE-7265: Improved test case by using PollingProber instead of Thread.sleep.
Merge pull request #314 from mulesoft/MULE-7265

MULE-7265: Stop already started message processors if one of the flow pr...