code: public static String getHostname() {
  		final String hostname = System.getProperty(HOSTNAME_PROPERTY);
  		// TODO : Ensure hostname format is valid.
  		return (hostname == null ? DEFAULT_HOSTNAME : hostname);
  	}
docs: Hostname getter, if user has defined a specific hostname through
  java system properties then it will be used. Otherwise the default
  hostname (https://code.google.com) will be returned.
  
  @return Hostname to use for performing request.