code: public function encodeValue(EncodePropertyValueFromWidgetEvent $event)
      {
          if (!$this->wantToHandle($event)) {
              return;
          }
  
          if (is_array($event->getValue())) {
              $values = [];
  
              foreach ($event->getValue() as $value) {
                  $values[] = substr($value, 6);
              }
  
              // Cut off the 'value_' prefix.
              $event->setValue($values);
          } else {
              // Cut off the 'value_' prefix.
              $event->setValue(substr($event->getValue(), 6));
          }
      }
docs: Translates an generated alias to the corresponding value.
  
  @param EncodePropertyValueFromWidgetEvent $event The event.
  
  @return void