code: public ClientCredentialsRequest.Builder clientCredentials() {
      return new ClientCredentialsRequest.Builder(clientId, clientSecret)
              .setDefaults(httpManager, scheme, host, port)
              .grant_type("client_credentials");
    }
docs: Returns a builder that can be used to build requests for client credential grants. <br>
  Requires client ID and client secret to be set.
  
  @return A {@link ClientCredentialsRequest.Builder}.