What is the URL for configuring OAuth2 services? If this is the code in oauth2_servers.services_auth.inc module, what is the url to enable the "require authentication" checkbox?

/**
 * Services authentication "controller_settings" callback.
 */
function oauth2_server_services_controller_settings($settings, $controller, $endpoint, $class, $name) {
  $form = array();
  $form['require_authentication'] = array(
    '#type' =&gt; 'checkbox',
    '#title' =&gt; t('Require authentication'),
    '#default_value' =&gt; isset($settings['require_authentication']) ? $settings['require_authentication'] : FALSE,
  );
  $form['scope'] = array(
    '#type' =&gt; 'textfield',
    '#title' =&gt; t('Scope'),
    '#default_value' =&gt; isset($settings['scope']) ? $settings['scope'] : '',
    '#description' =&gt; t('A space-separated list of required scopes. Leave empty to ignore the check.'),
  );

  return $form;
You enable OAuth2 authentication in admin/structure/services/list/$yourserver, then on the Authentication tab (admin/structure/services/list/$yourserver/authentication) you select the OAuth2 server.
After that, once you go to the Resources tab (admin/structure/services/list/$yourserver/resources) you will see the mentioned settings in the Settings column for each resource.

Make sure that you have the latest -dev release of Services, or the patch mentioned on the OAuth2 Server project page applied, otherwise it won't work.