Resolve #3470021 "Class calendarpager is"

Closes #3470021

src/Plugin/views/pager/CalendarPager.php

@@ -137,6 +137,13 @@ class CalendarPager extends PagerPluginBase {
     ];
   }
 
+  /**
+   * Returns a string to display as the clickable title for the pager plugin.
+   */
+  public function summaryTitle() {
+    return $this->t('Settings');
+  }
+
   /**
    * {@inheritdoc}
    */