code: public List<Message> removeAwaitingMessages( Instance instance ) {
  
  		Instance scopedInstance = InstanceHelpers.findScopedInstance( instance );
  		List<Message> result = null;
  
  		// We reduce the spent time in the synchronized section.
  		synchronized( this.scopedInstanceToAwaitingMessages ) {
  			result = this.scopedInstanceToAwaitingMessages.remove( scopedInstance );
  		}
  
  		return result != null ? result : new ArrayList<Message>( 0 );
  	}
docs: Removes all the waiting messages for a given instance.
  <p>
  Can be called concurrently with {@link #storeAwaitingMessage(Instance, Message)}.
  </p>
  
  @param instance an instance (any instance is fine, the root will be determined)
  @return a non-null list