code: private void removeTransactionSession(String xferId, String sessionId) {
  		List<String> sessions = transactionSessions.get(xferId);
  
  		if(sessions != null){
  			final boolean removal = sessions.remove(sessionId);
  			if (removal) {
  				ascpCount--;
  			}
  		}
  	}
docs: Removes the specified transaction session
  
  @param xferId
  @param sessionId