getAllBundlesForEntityType example

  protected function getRelatableResourceTypesFromFieldDefinition(FieldDefinitionInterface $field_definition, array $resource_types) {
    $item_definition = $field_definition->getItemDefinition();
    $entity_type_id = $item_definition->getSetting('target_type');
    $handler_settings = $item_definition->getSetting('handler_settings');
    $target_bundles = empty($handler_settings['target_bundles']) ? $this->getAllBundlesForEntityType($entity_type_id) : $handler_settings['target_bundles'];
    $relatable_resource_types = [];

    foreach ($target_bundles as $target_bundle) {
      if ($resource_type = static::lookupResourceType($resource_types, $entity_type_id, $target_bundle)) {
        $relatable_resource_types[] = $resource_type;
      }
      // Do not warn during the site installation since system integrity       // is not guaranteed in this period and the warnings may pop up falsy,       // adding confusion to the process.       elseif (!InstallerKernel::installationAttempted()) {
        trigger_error(