code: private boolean isNewSession(String xferId, String sessionId) {
  		List<String> currentSessions = transactionSessions.get(xferId);
  
  		if(currentSessions == null) {
  			List<String> sessions = new ArrayList<String>();
  			sessions.add(sessionId);
  			transactionSessions.put(xferId, sessions);
  			return true;
  		} else if (!currentSessions.contains(sessionId)) {
  			currentSessions.add(sessionId);
  			return true;
  		} else {
  			return false;
  		}
  
  	}
docs: Return true if new session for transaction
  
  @param xferId
  @param sessionId
  @return boolean