ci: pro forma check of existence of internal method

createNode() is protected and used by Folder, but being an internal-only
method it shall not be exposed in the Folder or IRootFolder interface.

Signed-off-by: Arthur Schiwon <blizzz@arthur-schiwon.de>

lib/private/Files/Node/Folder.php

@@ -40,6 +40,7 @@ use OC\Files\Utils\PathHelper;
 use OCP\Files\Cache\ICacheEntry;
 use OCP\Files\FileInfo;
 use OCP\Files\Mount\IMountPoint;
+use OCP\Files\Node as INode;
 use OCP\Files\NotFoundException;
 use OCP\Files\NotPermittedException;
 use OCP\Files\Search\ISearchBinaryOperator;
@@ -109,12 +110,7 @@ class Folder extends Node implements \OCP\Files\Folder {
 		}, $folderContent);
 	}
 
-	/**
-	 * @param string $path
-	 * @param FileInfo $info
-	 * @return File|Folder
-	 */
-	protected function createNode($path, FileInfo $info = null, bool $infoHasSubMountsIncluded = true) {
+	protected function createNode(string $path, ?FileInfo $info = null, bool $infoHasSubMountsIncluded = true): INode {
 		if (is_null($info)) {
 			$isDir = $this->view->is_dir($path);
 		} else {
@@ -330,6 +326,12 @@ class Folder extends Node implements \OCP\Files\Folder {
 	 * @return array
 	 */
 	protected function getByIdInRootMount(int $id): array {
+		if (!method_exists($this->root, 'createNode')) {
+			// Always expected to be false. Being a method of Folder, this is
+			// always implemented. For it is an internal method and should not
+			// be exposed and made public, it is not part of an interface.
+			return [];
+		}
 		$mount = $this->root->getMount('');
 		$storage = $mount->getStorage();
 		$cacheEntry = $storage?->getCache($this->path)->get($id);
@@ -385,7 +387,7 @@ class Folder extends Node implements \OCP\Files\Folder {
 	/**
 	 * @param int $limit
 	 * @param int $offset
-	 * @return \OCP\Files\Node[]
+	 * @return INode[]
 	 */
 	public function getRecent($limit, $offset = 0) {
 		$filterOutNonEmptyFolder = new SearchBinaryOperator(