Add a "Manage permissions" tab for each bundle that has associated permissions

core/lib/Drupal/Core/Entity/Enhancer/EntityBundleRouteEnhancer.php

+<?php
+
+namespace Drupal\Core\Entity\Enhancer;
+
+use Drupal\Core\Routing\EnhancerInterface;
+use Drupal\Core\Routing\RouteObjectInterface;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\Routing\Route;
+
+/**
+ * Sets the bundle parameter for routes with the _field_ui option.
+ */
+class EntityBundleRouteEnhancer implements EnhancerInterface {
+
+  /**
+   * The entity type manager service.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+   */
+  protected $entityTypeManager;
+
+  /**
+   * Constructs a EntityBundleRouteEnhancer object.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
+   *   The entity type manager service.
+   */
+  public function __construct(EntityTypeManagerInterface $entity_type_manager) {
+    $this->entityTypeManager = $entity_type_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function enhance(array $defaults, Request $request) {
+    if (!$this->applies($defaults[RouteObjectInterface::ROUTE_OBJECT])) {
+      return $defaults;
+    }
+    if (($bundle = $this->entityTypeManager->getDefinition($defaults['entity_type_id'])->getBundleEntityType()) && isset($defaults[$bundle])) {
+      // Field UI forms only need the actual name of the bundle they're dealing
+      // with, not an upcasted entity object, so provide a simple way for them
+      // to get it.
+      $defaults['bundle'] = $defaults['_raw_variables']->get($bundle);
+    }
+
+    return $defaults;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function applies(Route $route) {
+    return ($route->hasOption('_field_ui'));
+  }
+
+}