cforge-2.0.x-dev/modules/cforge_docs/cforge_docs.module

<?php

use Drupal\Core\Access\AccessResult;

/**
 * Implements hook_node_access().
 * Prevent anon from seeing document nodes.
 */
function cforge_docs_node_access($node, $op, $account) {
  if ($op == 'view' and $node->bundle() == 'document') {
    return AccessResult::forbiddenIf($account->isAnonymous());
  }
  return AccessResult::neutral();
}