/**
   * adds a new output
   *
   * @param userId user id
   * @param hostSystemId host system id
   * @param c character
   */
  public static void addCharToOutput(Long userId, Long hostSystemId, char c) {

    UserSessionsOutput userSessionsOutput = userSessionsOutputMap.get(userId);
    if (userSessionsOutput != null) {
      SessionOutput sessionOutput = userSessionsOutput.getSessionOutputMap().get(hostSystemId);
      if (sessionOutput != null) {
        sessionOutput.setOutput(sessionOutput.getOutput() + Character.toString(c));
      }
    }
  }
  /**
   * adds a new output
   *
   * @param userId user id
   * @param sessionOutput session output object
   */
  public static void addOutput(Long userId, SessionOutput sessionOutput) {

    UserSessionsOutput userSessionsOutput = userSessionsOutputMap.get(userId);
    if (userSessionsOutput == null) {
      userSessionsOutputMap.put(userId, new UserSessionsOutput());
      userSessionsOutput = userSessionsOutputMap.get(userId);
    }
    userSessionsOutput.getSessionOutputMap().put(sessionOutput.getHostSystemId(), sessionOutput);
  }