Added links to admin menu for managing taxonomies

opencase.links.menu.yml

@@ -40,6 +40,11 @@ opencase.opencase_admin_menu:
   route_name: opencase.opencase_admin_menu
   menu_name: opencase 
   weight: 100
+opencase.manage_taxonomy_links:
+  class: Drupal\opencase\Plugin\Menu\ManageTaxonomyMenuLink
+  deriver: Drupal\opencase\Plugin\Derivative\ManageTaxonomyMenuLink
+  menu_name: opencase
+  parent: opencase.opencase_admin_menu
 opencase.manage_user_logins:
   title: 'Manage user logins'
   description: 'Manage who can access the system'

src/Plugin/Derivative/ManageTaxonomyMenuLink.php

@@ -0,0 +1,52 @@
+<?php
+
+namespace Drupal\opencase\Plugin\Derivative;
+
+use Drupal\Component\Plugin\Derivative\DeriverBase;
+use Drupal\Core\Plugin\Discovery\ContainerDeriverInterface;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+class ManageTaxonomyMenuLink extends DeriverBase implements ContainerDeriverInterface {
+
+  /**
+   * @var EntityTypeManagerInterface $entityTypeManager.
+   */
+
+  protected $entityTypeManager;
+  
+  /**
+   * Creates a AddEventsMenuLink instance.
+   *
+   * @param $base_plugin_id
+   * @param EntityTypeManagerInterface $entity_type_manager
+   */
+  public function __construct($base_plugin_id, EntityTypeManagerInterface $entity_type_manager) {
+    $this->entityTypeManager = $entity_type_manager;
+  }
+
+ /**
+   * {@inheritdoc}
+   */
+ public static function create(ContainerInterface $container, $base_plugin_id) {
+   return new static(
+    $base_plugin_id,
+    $container->get('entity_type.manager')
+   );
+ }
+  /**
+   * {@inheritdoc}
+   */
+  public function getDerivativeDefinitions($base_plugin_definition) {
+    $links = [];
+    $vocabs = $this->entityTypeManager->getStorage('taxonomy_vocabulary')->loadMultiple();
+    foreach ($vocabs as $id => $vocab) {
+      $links[$id] = [
+        'title' => 'Manage ' . $vocab->label(),
+        'route_name' => "entity.taxonomy_vocabulary.overview_form",
+        'route_parameters' => ['taxonomy_vocabulary' => $vocab->id()]
+      ] + $base_plugin_definition;
+    }
+    return $links;
+  }
+}

src/Plugin/Menu/ManageTaxonomyMenuLink.php

@@ -0,0 +1,6 @@
+<?php
+namespace Drupal\opencase\Plugin\Menu;
+ 
+use Drupal\Core\Menu\MenuLinkDefault;
+ 
+class ManageTaxonomyMenuLink extends MenuLinkDefault {}