version of the OAuth2 Server library could not be detected.

Regardless of how the Libraries report page displays, I found everything to be working, studying the init() function below, when I deleted the library directory, it for sure triggered the warning/error message therein. Put it back and all was fine. Closing.

/**
 * Implements hook_init().
 *
 * Nags the user about the missing library on OAuth2 admin pages.
 */
function oauth2_server_init() {
  $item = menu_get_item();
  if (is_array($item)) {
    if ($item['access'] && strpos($item['path'], 'admin/structure/oauth2-servers') === 0) {
      $path = oauth2_server_get_library_path();
      // Check for the existence of one file from the library.
      if (!$path || !file_exists($path . '/src/OAuth2/Server.php')) {
        $message = t('The OAuth2 server library is required for the OAuth2 module to function.
        Download the library from <a href="https://github.com/bshaffer/oauth2-server-php" target="_blank">GitHub</a> and place it in <em>!path</em>.', array('!path' => $path));
        drupal_set_message($message, 'error');
      }
    }
  }
}