code: public function handle(BuildDataDefinitionEvent $event)
      {
          if (($event->getContainer()->getName() !== 'tl_metamodel_searchable_pages')) {
              return;
          }
  
          foreach ($event->getContainer()->getPalettesDefinition()->getPalettes() as $palette) {
              foreach ($palette->getProperties() as $property) {
                  if ($property->getName() != 'filterparams') {
                      continue;
                  }
  
                  $chain = $property->getVisibleCondition();
                  if (!($chain
                      && ($chain instanceof PropertyConditionChain)
                      && $chain->getConjunction() == PropertyConditionChain::AND_CONJUNCTION
                  )
                  ) {
                      $chain = new PropertyConditionChain(
                          $chain ?: array(),
                          PropertyConditionChain::AND_CONJUNCTION
                      );
  
                      $property->setVisibleCondition($chain);
                  }
  
                  $chain->addCondition(new NotCondition(new PropertyValueCondition('filter', 0)));
                  break;
              }
          }
      }
docs: Build the data definition palettes.
  
  @param BuildDataDefinitionEvent $event The event.
  
  @return void