code: @SuppressWarnings("WeakerAccess")
      public ParameterizableRequest<Credentials, AuthenticationException> renewAuth(@NonNull String refreshToken) {
          final Map<String, Object> parameters = ParameterBuilder.newBuilder()
                  .setClientId(getClientId())
                  .setRefreshToken(refreshToken)
                  .setGrantType(auth0.isOIDCConformant() ? ParameterBuilder.GRANT_TYPE_REFRESH_TOKEN : ParameterBuilder.GRANT_TYPE_JWT)
                  .asDictionary();
  
          HttpUrl url;
          if (auth0.isOIDCConformant()) {
              url = HttpUrl.parse(auth0.getDomainUrl()).newBuilder()
                      .addPathSegment(OAUTH_PATH)
                      .addPathSegment(TOKEN_PATH)
                      .build();
          } else {
              url = HttpUrl.parse(auth0.getDomainUrl()).newBuilder()
                      .addPathSegment(DELEGATION_PATH)
                      .build();
          }
  
          return factory.POST(url, client, gson, Credentials.class, authErrorBuilder)
                  .addParameters(parameters);
      }
docs: Requests new Credentials using a valid Refresh Token. The received token will have the same audience and scope as first requested. How the new Credentials are requested depends on the {@link Auth0#isOIDCConformant()} flag.
  - If the instance is OIDC Conformant the endpoint will be /oauth/token with 'refresh_token' grant, and the response will include an id_token and an access_token if 'openid' scope was requested when the refresh_token was obtained.
  - If the instance is not OIDC Conformant the endpoint will be /delegation with 'urn:ietf:params:oauth:grant-type:jwt-bearer' grant, and the response will include an id_token.
  Example usage:
  <pre>
  {@code
  client.renewAuth("{refresh_token}")
  .addParameter("scope", "openid profile email")
  .start(new BaseCallback<Credentials>() {
  {@literal}Override
  public void onSuccess(Credentials payload) { }
  
  {@literal}@Override
  public void onFailure(AuthenticationException error) { }
  });
  }
  </pre>
  
  @param refreshToken used to fetch the new Credentials.
  @return a request to start