Issue #3508229: Fix PHP 8.4 implicit nullable deprecation

Closes #3508229

src/Tree/EntityTreeBuilder.php

@@ -35,14 +35,19 @@ class EntityTreeBuilder implements TreeBuilderInterface {
    *
    * @param string $entityType
    *   The type of the entity.
-   *
    * @param string $bundleID
    *   The bundle ID.
+   * @param string|null $langCode
+   *   The language code.
+   * @param int $parent
+   *   The parent entity ID.
+   * @param int|null $max_depth
+   *   The maximum depth of the tree.
    *
    * @return array
    *   All entities in the entity bundle.
    */
-  public function loadTree(string $entityType, string $bundleID, string $langCode = NULL, int $parent = 0, int $max_depth = NULL) {
+  public function loadTree(string $entityType, string $bundleID, ?string $langCode = NULL, int $parent = 0, ?int $max_depth = NULL) {
     if ($this->hasAccess()) {
       if ($bundleID === '*') {
         // Load all entities regardless bundles.
@@ -148,14 +153,14 @@ class EntityTreeBuilder implements TreeBuilderInterface {
   /**
    * Check if a user has the access to the tree.
    *
-   * @param \Drupal\Core\Session\AccountProxyInterface $user
+   * @param \Drupal\Core\Session\AccountProxyInterface|null $user
    *   The user object to check.
    *
    * @return bool
    *   If the user has the access to the tree return TRUE,
    *   otherwise return FALSE.
    */
-  private function hasAccess(AccountProxyInterface $user = NULL) {
+  private function hasAccess(?AccountProxyInterface $user = NULL) {
     // Check current user as default.
     if (empty($user)) {
       $user = \Drupal::currentUser();