bundle_name.php

<?php

// Got list of entity definition by below:
$entity_manager = Drupal::entityManager();

// While foreaching them, we want to know entities that are fieldable.
      foreach ($entity_manager->getDefinitions() as $entity_info) {
        if ($entity_info['fieldable'] && isset($entity_info['route_base_path'])) {
// now I can get the URL as admin/structure/contact/manage/{bundle}.
// is there anyway to get the available {bundle} here and foreach them?
// So that I can get admin/structure/contact/manage/feedback and admin/structure/contact/manage/sitewide etc?