code: public String userAgent() {
          return String.format("Azure-SDK-For-Java/%s OS:%s MacAddressHash:%s Java:%s",
                  getClass().getPackage().getImplementationVersion(),
                  OS,
                  MAC_ADDRESS_HASH,
                  JAVA_VERSION);
      }
docs: The default User-Agent header. Override this method to override the user agent.
  
  @return the user agent string.