code: public static String getUserAgent(String customUserAgent) {
          Properties systemProperties;
          try {
              systemProperties = System.getProperties();
          } catch (SecurityException e) {
              logger.debug("Unable to determine JVM version due to security restrictions.");
              systemProperties = null;
          }
          return internalGetUserAgent(systemProperties, customUserAgent);
      }
docs: Returns the user agent string.  Format is "(SDK name)/(SDK version) (Language)/(Language version)"
  Custom user agent will be appended to the end of the standard user agent.
  
  @param customUserAgent custom user agent to append to end of standard user agent
  @return user agent string