Issue #2872562 by kala4ek, arunkumark, Chi:...

Issue #2872562 by kala4ek, arunkumark, Chi: Drupal\views\Plugin\views\style\StylePluginBase::renderGroupingSets() incorrect documentation

core/modules/views/src/Plugin/views/style/StylePluginBase.php

@@ -482,8 +482,8 @@ public function render() {
    *   - level: The hierarchical level of the grouping.
    *   - rows: The result rows to be rendered in this group..
    *
-   * @return string
-   *   Rendered output of given grouping sets.
+   * @return array
+   *   Render array of grouping sets.
    */
   public function renderGroupingSets($sets) {
     $output = [];