Add support for 10.1 location structure

src/RemoteMenuParser.php

@@ -84,7 +84,8 @@ class RemoteMenuParser {
     $data = [];
     // Convert a flat JSON into a tree array.
     foreach ($json_parsed->linkset[0]->item as $item) {
-      $data = static::insertLink($item->{'drupal-menu-hierarchy'}[0], $item->href, $item->title, $data);
+      $location = static::parseLocation($item);
+      $data = static::insertLink($location, $item->href, $item->title, $data);
     }
     // Convert the tree array into a tree of RemoteMenuLink objects.
     $base_url = parse_url($url, PHP_URL_SCHEME) . '://' . parse_url($url, PHP_URL_HOST);
@@ -145,7 +146,7 @@ class RemoteMenuParser {
    */
   protected static function insertLink(string $location, string $link, string $title, array $data): array {
     $pointer = &$data;
-    $fragments = array_filter(explode('.', $location));
+    $fragments = array_filter(explode('.', $location), 'strlen');
     // Traverse the tree.
     while (TRUE) {
       if (count($fragments) === 1) {
@@ -165,4 +166,24 @@ class RemoteMenuParser {
     return $data;
   }
 
+  /**
+   * Parses the location string.
+   *
+   * @param object $item
+   *   The menu item object.
+   *
+   * @return string
+   *   The location string.
+   */
+  protected static function parseLocation(object $item): string {
+    if (property_exists($item, 'drupal-menu-hierarchy')) {
+      // This is the behaviour in contrib module decoupled_menus.
+      return $item->{'drupal-menu-hierarchy'}[0];
+    }
+    // This is the behaviour in 10.1 and onwards.
+    assert(property_exists($item, 'hierarchy'));
+    $hierarchy_array = $item->hierarchy;
+    return '.' . implode('.', $hierarchy_array);
+  }
+
 }