diff --git a/core/modules/views/lib/Drupal/views/Plugin/views/filter/FilterPluginBase.php b/core/modules/views/lib/Drupal/views/Plugin/views/filter/FilterPluginBase.php
index e0dd2d5..2f9741c 100644
--- a/core/modules/views/lib/Drupal/views/Plugin/views/filter/FilterPluginBase.php
+++ b/core/modules/views/lib/Drupal/views/Plugin/views/filter/FilterPluginBase.php
@@ -733,7 +733,7 @@ function build_group_options() {
    * Build a form containing a group of operator | values to apply as a
    * single filter.
    */
-  function group_form(&$form, &$form_state) {
+  public function groupForm(&$form, &$form_state) {
     if (!empty($this->options['group_info']['optional']) && !$this->multipleExposedInput()) {
 
       $old_any = $this->options['group_info']['widget'] == 'select' ? '<Any>' : '&lt;Any&gt;';
diff --git a/core/modules/views/views.module b/core/modules/views/views.module
index 09d8c6e..f8e2aa4 100644
--- a/core/modules/views/views.module
+++ b/core/modules/views/views.module
@@ -1448,7 +1448,7 @@ function views_exposed_form($form, &$form_state) {
         // When an user choose an option the selected value is split
         // into the operator and value that the item represents.
         if ($handler->isAGroup()) {
-          $handler->group_form($form, $form_state);
+          $handler->groupForm($form, $form_state);
           $id = $handler->options['group_info']['identifier'];
         }
         else {