Issue #3500177 - Add new page

Related to #3500177

src/Controller/FapiValidationController.php

+<?php
+
+namespace Drupal\fapi_validation\Controller;
+
+use Drupal\Core\Controller\ControllerBase;
+use Drupal\fapi_validation\FapiValidationValidatorsManager;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Returns a table with all fapi validation plugins.
+ */
+class FapiValidationController extends ControllerBase {
+
+  /**
+   * Returns the plugin.manager.fapi_validation_validators service.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+   */
+  protected $validationManager;
+
+  /**
+   * Constructs a FapiValidationController object.
+   *
+   * @param \Drupal\fapi_validation\FapiValidationValidatorsManager $validation_manager
+   * *   A plugin manager for Fapi Validation Validators Plugin.
+ */
+  public function __construct(FapiValidationValidatorsManager $validation_manager) {
+    $this->validationManager = $validation_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('plugin.manager.fapi_validation_validators')
+    );
+  }
+
+  /**
+   * Show all validation plugins.
+   */
+  public function validations() {
+    $header = [
+      ['data' => $this->t('ID')],
+      ['data' => $this->t('Label')],
+      ['data' => $this->t('Description')],
+      ['data' => $this->t('Provider')],
+    ];
+
+    $rows = [];
+    foreach ($this->validationManager->getDefinitions() as $validation) {
+      $rows[] = [
+        $validation['id'],
+        $validation['label'] ?? '',
+        $validation['description'] ?? '',
+        $validation['provider'],
+      ];
+    }
+
+    return [
+      '#theme' => 'table',
+      '#header' => $header,
+      '#rows' => $rows,
+    ];
+  }
+
+}