diff --git a/core/lib/Drupal/Component/Plugin/Factory/DefaultFactory.php b/core/lib/Drupal/Component/Plugin/Factory/DefaultFactory.php
index 2315a7f..044bfb7 100644
--- a/core/lib/Drupal/Component/Plugin/Factory/DefaultFactory.php
+++ b/core/lib/Drupal/Component/Plugin/Factory/DefaultFactory.php
@@ -77,11 +77,24 @@ public function createInstance($plugin_id, array $configuration = array()) {
    *
    */
   public static function getPluginClass($plugin_id, $plugin_definition = NULL, $required_interface = NULL) {
-    if (empty($plugin_definition['class'])) {
-      throw new PluginException(sprintf('The plugin (%s) did not specify an instance class.', $plugin_id));
+    $missing_class_message = sprintf('The plugin (%s) did not specify an instance class.', $plugin_id);
+    if (is_array($plugin_definition)) {
+      if (empty($plugin_definition['class'])) {
+        throw new PluginException($missing_class_message);
+      }
+
+      $class = $plugin_definition['class'];
     }
+    elseif (is_object($plugin_definition) && method_exists($plugin_definition, 'getClass')) {
+      if (!$plugin_definition->getClass()) {
+        throw new PluginException($missing_class_message);
+      }
 
-    $class = $plugin_definition['class'];
+      $class = $plugin_definition->getClass();
+    }
+    else {
+      throw new PluginException($missing_class_message);
+    }
 
     if (!class_exists($class)) {
       throw new PluginException(sprintf('Plugin (%s) instance class "%s" does not exist.', $plugin_id, $class));