code: protected function getWidgetClass($field)
      {
          $className = $GLOBALS[(TL_MODE == 'BE' ? 'BE_FFL' : 'TL_FFL')][$field['inputType']];
  
          if (($className !== '') && class_exists($className)) {
              return $className;
          }
  
          return null;
      }
docs: Retrieve the widget class if it is valid.
  
  @param array $field The field information.
  
  @return string
  
  @SuppressWarnings(PHPMD.Superglobals)
  @SuppressWarnings(PHPMD.CamelCaseVariableName)