Added menu links and admin page for configuring event series.

recurring_events.links.menu.yml

+# Parent Menu Structure.
+events.admin.overview:
+  title: 'Events'
+  description: 'Configure Event Series and Instances.'
+  route_name: events.admin.overview
+  parent: system.admin_structure
+
+# Events Series settings admin page.
+events.admin.structure.settings:
+  title: 'Event Series'
+  description: 'Configure Event Series Entity'
+  route_name:  eventseries.settings
+  parent: events.admin.overview

recurring_events.links.task.yml

+# Events Series settings admin page.
+eventseries.settings_tab:
+  route_name: eventseries.settings
+  title: Event Series Settings
+  base_route: eventseries.settings
\ No newline at end of file

recurring_events.routing.yml

@@ -56,6 +56,15 @@ entity.eventseries.collection:
   # Checks for permission directly.
     _permission: 'access eventseries overview'
 
+# Admin Menu Strucutre.
+events.admin.overview:
+  path: '/admin/structure/events'
+  defaults:
+    _title: 'Events Management'
+    _controller: '\Drupal\recurring_events\Controller\EventController::adminPage'
+  requirements:
+    _permission: 'access administration pages'
+
 # Event Series settings admin page.
 eventseries.settings:
   path: '/admin/structure/events/series/settings'

src/Controller/EventController.php

+<?php
+
+namespace Drupal\recurring_events\Controller;
+
+use Drupal\Core\Controller\ControllerBase;
+use Drupal\Core\Datetime\DateFormatterInterface;
+use Drupal\Core\DependencyInjection\ContainerInjectionInterface;
+use Drupal\Core\Render\RendererInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Drupal\system\SystemManager;
+
+/**
+ * The EventController class.
+ */
+class EventController extends ControllerBase implements ContainerInjectionInterface {
+
+  /**
+   * The date formatter service.
+   *
+   * @var \Drupal\Core\Datetime\DateFormatterInterface
+   */
+  protected $dateFormatter;
+
+  /**
+   * The renderer service.
+   *
+   * @var \Drupal\Core\Render\RendererInterface
+   */
+  protected $renderer;
+
+  /**
+   * System Manager Service.
+   *
+   * @var \Drupal\system\SystemManager
+   */
+  protected $systemManager;
+
+  /**
+   * Constructs a EventController object.
+   *
+   * @param \Drupal\Core\Datetime\DateFormatterInterface $date_formatter
+   *   The date formatter service.
+   * @param \Drupal\Core\Render\RendererInterface $renderer
+   *   The renderer service.
+   * @param \Drupal\system\SystemManager $systemManager
+   *   System manager service.
+   */
+  public function __construct(DateFormatterInterface $date_formatter, RendererInterface $renderer, SystemManager $systemManager) {
+    $this->dateFormatter = $date_formatter;
+    $this->renderer = $renderer;
+    $this->systemManager = $systemManager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('date.formatter'),
+      $container->get('renderer'),
+      $container->get('system.manager')
+    );
+  }
+
+  /**
+   * The page callback for the admin overview page.
+   */
+  public function adminPage() {
+    return $this->systemManager->getBlockContents();
+  }
+
+}

src/Entity/EventSeries.php

@@ -422,7 +422,6 @@ class EventSeries extends EditorialContentEntityBase implements EventInterface {
       ->setTranslatable(FALSE)
       ->setDisplayOptions('view', [
         'label' => 'above',
-        'type' => 'entity_reference',
         'weight' => 10,
       ])
       ->setDisplayConfigurable('view', TRUE)