Issue #2927856 by kevin.dutra, Neslee Canil Pinto: String filters don't receive BEF treatment

src/Plugin/better_exposed_filters/filter/FilterWidgetBase.php

@@ -31,7 +31,7 @@ abstract class FilterWidgetBase extends BetterExposedFiltersWidgetBase implement
     }
 
     // Check various filter types and determine what options are available.
-    if (is_a($filter, 'Drupal\views\Plugin\views\filter\String') || is_a($filter, 'Drupal\views\Plugin\views\filter\InOperator')) {
+    if (is_a($filter, 'Drupal\views\Plugin\views\filter\StringFilter') || is_a($filter, 'Drupal\views\Plugin\views\filter\InOperator')) {
       if (in_array($filter->operator, ['in', 'or', 'and', 'not'])) {
         $is_applicable = TRUE;
       }