diff --git a/core/lib/Drupal/Component/Plugin/Factory/DefaultFactory.php b/core/lib/Drupal/Component/Plugin/Factory/DefaultFactory.php
index dee9f26..6753135 100644
--- a/core/lib/Drupal/Component/Plugin/Factory/DefaultFactory.php
+++ b/core/lib/Drupal/Component/Plugin/Factory/DefaultFactory.php
@@ -89,7 +89,7 @@ public static function getPluginClass($plugin_id, $plugin_definition = NULL, $re
     }
 
     if ($required_interface && !is_subclass_of($plugin_definition['class'], $required_interface)) {
-      throw new PluginException(sprintf('Plugin "%s" (%s) in %s should implement interface %s.', $plugin_id, $plugin_definition['class'], $plugin_definition['provider'], is_array($required_interface) ? implode(', ', $required_interface) : $required_interface));
+      throw new PluginException(sprintf('Plugin "%s" (%s) in %s should implement interface %s.', $plugin_id, $plugin_definition['class'], $plugin_definition['provider'], $required_interface));
     }
 
     return $class;
diff --git a/core/lib/Drupal/Core/Archiver/ArchiverManager.php b/core/lib/Drupal/Core/Archiver/ArchiverManager.php
index a457a1f..b8ac88c 100644
--- a/core/lib/Drupal/Core/Archiver/ArchiverManager.php
+++ b/core/lib/Drupal/Core/Archiver/ArchiverManager.php
@@ -33,7 +33,7 @@ class ArchiverManager extends DefaultPluginManager {
    *   The module handler to invoke the alter hook with.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
-    parent::__construct('Plugin/Archiver', $namespaces, $module_handler, 'Drupal\Core\Archiver\Annotation\Archiver');
+    parent::__construct('Plugin/Archiver', $namespaces, $module_handler, 'Drupal\Core\Archiver\ArchiverInterface', 'Drupal\Core\Archiver\Annotation\Archiver');
     $this->alterInfo('archiver_info');
     $this->setCacheBackend($cache_backend, 'archiver_info_plugins');
   }
diff --git a/core/tests/Drupal/Tests/Component/Plugin/DefaultFactoryTest.php b/core/tests/Drupal/Tests/Component/Plugin/DefaultFactoryTest.php
index ed53798..21dcf7c 100644
--- a/core/tests/Drupal/Tests/Component/Plugin/DefaultFactoryTest.php
+++ b/core/tests/Drupal/Tests/Component/Plugin/DefaultFactoryTest.php
@@ -17,8 +17,6 @@ class DefaultFactoryTest extends UnitTestCase {
 
   /**
    * Tests getPluginClass() with a valid plugin.
-   *
-   * @covers ::getPluginClass
    */
   public function testGetPluginClassWithValidPlugin() {
     $plugin_class = 'Drupal\plugin_test\Plugin\plugin_test\fruit\Cherry';
@@ -30,8 +28,6 @@ public function testGetPluginClassWithValidPlugin() {
   /**
    * Tests getPluginClass() with a missing class definition.
    *
-   * @covers ::getPluginClass
-   *
    * @expectedException \Drupal\Component\Plugin\Exception\PluginException
    * @expectedExceptionMessage The plugin (cherry) did not specify an instance class.
    */
@@ -42,8 +38,6 @@ public function testGetPluginClassWithMissingClass() {
   /**
    * Tests getPluginClass() with a not existing class definition.
    *
-   * @covers ::getPluginClass
-   *
    * @expectedException \Drupal\Component\Plugin\Exception\PluginException
    * @expectedExceptionMessage Plugin (kiwifruit) instance class "\Drupal\plugin_test\Plugin\plugin_test\fruit\Kiwifruit" does not exist.
    */
@@ -53,8 +47,6 @@ public function testGetPluginClassWithNotExistingClass() {
 
   /**
    * Tests getPluginClass() with a required interface.
-   *
-   * @covers ::getPluginClass
    */
   public function testGetPluginClassWithInterface() {
     $plugin_class = 'Drupal\plugin_test\Plugin\plugin_test\fruit\Cherry';
@@ -66,8 +58,6 @@ public function testGetPluginClassWithInterface() {
   /**
    * Tests getPluginClass() with a required interface but no implementation.
    *
-   * @covers ::getPluginClass
-   *
    * @expectedException \Drupal\Component\Plugin\Exception\PluginException
    * @expectedExceptionMessage Plugin "cherry" (Drupal\plugin_test\Plugin\plugin_test\fruit\Kale) in core should implement interface \Drupal\plugin_test\Plugin\plugin_test\fruit\FruitInterface.
    */