Merge pull request #823 from mulesoft/MULE-7728

MULE-7728: Several improvements:
(cherry picked from commit 8f1b4b37add6be635613ae7cdb319aaaac88da6e)

Conflicts:
	core/src/main/java/org/mule/routing/correlation/EventCorrelator.java
	core/src/main/java/org/mule/util/store/MuleDefaultObjectStoreFactory.java
	core/src/test/java/org/mule/routing/correlation/EventCorrelatorTestCase.java