Get rid of hardcoded bundle field name to prevent potential compatible issue...

Get rid of hardcoded bundle field name to prevent potential compatible issue with entity types defined by other contributed modules

src/Tree/EntityTreeBuilder.php

@@ -41,6 +41,7 @@ class EntityTreeBuilder implements TreeBuilderInterface {
       }
       else {
         $hasBundle = TRUE;
+        $entityStorage = \Drupal::entityTypeManager()->getStorage($entityType);
         // Build the tree node for the bundle.
         $tree = [
             (object) [
@@ -51,14 +52,13 @@ class EntityTreeBuilder implements TreeBuilderInterface {
                 'text' => $bundleID,
             ],
         ];
-        // The bundle field of node calls 'type'.
-        $bundleName = ($entityType === 'node') ? 'type' : 'bundle';
         // Entity query properties.
         $properties = [
-          $bundleName => $bundleID,
+            // Bundle key field.
+            $entityStorage->getEntityType()->getKey('bundle') => $bundleID,
         ];
         // Load all entities matched the conditions.
-        $entities = \Drupal::entityTypeManager()->getStorage($entityType)->loadByProperties($properties);
+        $entities = $entityStorage->loadByProperties($properties);
       }
       
       // Buld the tree.