LPS-51975 add reentrant lock to public method to prevent concurrent modi...

...fication of notificationEvents

Buildfile: d:\repo\portal\portal-impl\build.xml

format-source:
     [copy] Copying 2 files to d:\repo\portal\portal-impl\classes
     [java] Loading file:/D:/repo/portal/portal-impl/classes/system.properties
     [java] Loading file:/D:/repo/portal/portal-impl/classes/portal.properties

BUILD SUCCESSFUL
Total time: 1 minute 6 seconds