code: public Client<? extends Options, ? extends OptionsBuilder, ? extends RequestBuilder> newClient() {
          if (clientClassName == null) {
              return new DefaultClient();
          } else {
              try {
                  return (Client) Thread.currentThread().getContextClassLoader().loadClass(clientClassName).newInstance();
              } catch (Exception e) {
                  throw new RuntimeException(e);
              }
          }
      }
docs: Return a new {@link Client} instance
  
  @return a new {@link Client} instance