Javadoc
The way servlet containers react to an exception that occurs in a
ServletRequestListener differs among servlet listeners. In certain containers
the destroyed callback may be invoked multiple times, causing the latter invocations to fail as thread locals have already been unset. We use the
#REQUEST_DESTROYED flag to indicate that all further invocations of the
ServletRequestListener#requestDestroyed(javax.servlet.ServletRequestEvent) should be ignored by Weld.