Merge pull request #673 from mulesoft/MULE-7575

MULE-7575 - using the latest values from session properties in aggregato...
(cherry picked from commit 91f69234a762935e86e8fc2a11d09189d5665190)

Conflicts:
	transports/http/src/test/java/org/mule/transport/http/functional/SessionPropertiesWithMessageCollectionTestCase.java

(cherry picked from commit 14a9a35bb1eff0599ff916876646e11686791c1d)

Conflicts:
	core/src/main/java/org/mule/routing/EventGroup.java