diff --git a/core/modules/views/lib/Drupal/views/Plugin/views/display/DisplayPluginBase.php b/core/modules/views/lib/Drupal/views/Plugin/views/display/DisplayPluginBase.php
index 4da5800..972f2fb 100644
--- a/core/modules/views/lib/Drupal/views/Plugin/views/display/DisplayPluginBase.php
+++ b/core/modules/views/lib/Drupal/views/Plugin/views/display/DisplayPluginBase.php
@@ -928,7 +928,7 @@ public function getFieldLabels($groupable_only = FALSE) {
     }
 
     foreach ($this->getHandlers('field') as $id => $handler) {
-      if ($groupable_only && !$handler->use_string_group_by()) {
+      if ($groupable_only && !$handler->useStringGroupBy()) {
         // Continue to next handler if it's not groupable.
         continue;
       }
diff --git a/core/modules/views/lib/Drupal/views/Plugin/views/field/FieldPluginBase.php b/core/modules/views/lib/Drupal/views/Plugin/views/field/FieldPluginBase.php
index bc8dfff..ddd5fa2 100644
--- a/core/modules/views/lib/Drupal/views/Plugin/views/field/FieldPluginBase.php
+++ b/core/modules/views/lib/Drupal/views/Plugin/views/field/FieldPluginBase.php
@@ -402,7 +402,7 @@ function get_value($values, $field = NULL) {
    * @return bool
    *  TRUE if this field handler is groupable, otherwise FALSE.
    */
-  function use_string_group_by() {
+  function useStringGroupBy() {
     return TRUE;
   }
 
@@ -1676,3 +1676,4 @@ public static function trimText($alter, $value) {
 /**
  * @}
  */
+