code: public static void addStandardTokens(TokenFilter filter, Credentials credentials) {
  
          // Add username token
          String username = credentials.getUsername();
          if (username != null)
              filter.setToken(USERNAME_TOKEN, username);
  
          // Add password token
          String password = credentials.getPassword();
          if (password != null)
              filter.setToken(PASSWORD_TOKEN, password);
  
          // Add client hostname token
          String hostname = credentials.getRemoteHostname();
          if (hostname != null)
              filter.setToken(CLIENT_HOSTNAME_TOKEN, hostname);
  
          // Add client address token
          String address = credentials.getRemoteAddress();
          if (address != null)
              filter.setToken(CLIENT_ADDRESS_TOKEN, address);
  
          // Add any tokens which do not require credentials
          addStandardTokens(filter);
  
      }
docs: Adds tokens which are standardized by guacamole-ext to the given
  TokenFilter using the values from the given Credentials object. These
  standardized tokens include the current username (GUAC_USERNAME),
  password (GUAC_PASSWORD), and the server date and time (GUAC_DATE and
  GUAC_TIME respectively). If either the username or password are not set
  within the given credentials, the corresponding token(s) will remain
  unset.
  
  @param filter
  The TokenFilter to add standard tokens to.
  
  @param credentials
  The Credentials to use when populating the GUAC_USERNAME and
  GUAC_PASSWORD tokens.