code: public TokenRequest setTokenServerUrl(GenericUrl tokenServerUrl) {
      this.tokenServerUrl = tokenServerUrl;
      Preconditions.checkArgument(tokenServerUrl.getFragment() == null);
      return this;
    }
docs: Sets the token server URL.
  
  <p>
  Overriding is only supported for the purpose of calling the super implementation and changing
  the return type, but nothing else.
  </p>