diff --git a/core/lib/Drupal/Core/Validation/Annotation/Constraint.php b/core/lib/Drupal/Core/Validation/Annotation/Constraint.php
index a5b022e..85c4344 100644
--- a/core/lib/Drupal/Core/Validation/Annotation/Constraint.php
+++ b/core/lib/Drupal/Core/Validation/Annotation/Constraint.php
@@ -13,7 +13,6 @@
  * Defines a validation constraint annotation object.
  *
  * @see \Drupal\Core\Validation\ConstraintManager
- * @see hook_validation_constraint_info_alter()
  *
  * @Annotation
  */
@@ -22,6 +21,9 @@ class Constraint extends Plugin {
   /**
    * The constraint plugin ID.
    *
+   * The plugin ID usually resembles the class name without the "Constraint"
+   * suffix.
+   *
    * @var string
    */
   public $id;
@@ -41,10 +43,10 @@ class Constraint extends Plugin {
    * type names. For supporting all types, FALSE may be specified. The key
    * defaults to an empty array, i.e. no types are supported.
    *
-   * @var mixed
+   * @var string|string[]|false
    *
    * @see \Drupal\Core\TypedData\Annotation\DataType
    */
-  public $types;
+  public $type = array();
 
-}
\ No newline at end of file
+}
diff --git a/core/lib/Drupal/Core/Validation/ConstraintManager.php b/core/lib/Drupal/Core/Validation/ConstraintManager.php
index 4b207fd..b6b0d16 100644
--- a/core/lib/Drupal/Core/Validation/ConstraintManager.php
+++ b/core/lib/Drupal/Core/Validation/ConstraintManager.php
@@ -26,10 +26,10 @@
  * module would have to prefix any constraints with "Profile".
  *
  * Constraint plugins may specify data types to which support is limited via the
- * 'type' key of plugin definitions. Valid values are any types registered via
- * the typed data API, or an array of multiple type names. For supporting all
- * types FALSE may be specified. The key defaults to an empty array, i.e. no
- * types are supported.
+ * 'type' key of plugin definitions. See
+ * \Drupal\Core\Validation\Annotation\Constraint for details.
+ *
+ * @see \Drupal\Core\Validation\Annotation\Constraint
  */
 class ConstraintManager extends DefaultPluginManager {
 
@@ -45,7 +45,7 @@ class ConstraintManager 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/Validation/Constraint', $namespaces, 'Drupal\Core\Validation\Annotation\Constraint');
+    parent::__construct('Plugin/Validation/Constraint', $namespaces, $module_handler, NULL, 'Drupal\Core\Validation\Annotation\Constraint');
     $this->discovery = new StaticDiscoveryDecorator($this->discovery, array($this, 'registerDefinitions'));
     $this->alterInfo('validation_constraint');
     $this->setCacheBackend($cache_backend, 'validation_constraint_plugins');
@@ -111,10 +111,7 @@ public function registerDefinitions() {
    */
   public function processDefinition(&$definition, $plugin_id) {
     // Make sure 'type' is set and either an array or FALSE.
-    if (!isset($definition['type'])) {
-      $definition['type'] = array();
-    }
-    elseif ($definition['type'] !== FALSE && !is_array($definition['type'])) {
+    if ($definition['type'] !== FALSE && !is_array($definition['type'])) {
       $definition['type'] = array($definition['type']);
     }
   }
diff --git a/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/EmailConstraint.php b/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/EmailConstraint.php
index 905d1b6..48a6f99 100644
--- a/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/EmailConstraint.php
+++ b/core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/EmailConstraint.php
@@ -14,7 +14,7 @@
  *
  * Overrides the symfony constraint to use the strict setting.
  *
- * @Plugin(
+ * @Constraint(
  *   id = "Email",
  *   label = @Translation("Email", context = "Validation")
  * )
diff --git a/core/modules/aggregator/src/Plugin/Validation/Constraint/FeedTitleConstraint.php b/core/modules/aggregator/src/Plugin/Validation/Constraint/FeedTitleConstraint.php
index 47d16ac..a8e71a2 100644
--- a/core/modules/aggregator/src/Plugin/Validation/Constraint/FeedTitleConstraint.php
+++ b/core/modules/aggregator/src/Plugin/Validation/Constraint/FeedTitleConstraint.php
@@ -12,7 +12,7 @@
 /**
  * Supports validating feed titles.
  *
- * @Plugin(
+ * @Constraint(
  *   id = "FeedTitle",
  *   label = @Translation("Feed title", context = "Validation")
  * )
diff --git a/core/modules/comment/src/Plugin/Validation/Constraint/CommentNameConstraint.php b/core/modules/comment/src/Plugin/Validation/Constraint/CommentNameConstraint.php
index 575a393..7b66245 100644
--- a/core/modules/comment/src/Plugin/Validation/Constraint/CommentNameConstraint.php
+++ b/core/modules/comment/src/Plugin/Validation/Constraint/CommentNameConstraint.php
@@ -12,7 +12,7 @@
 /**
  * Supports validating comment author names.
  *
- * @Plugin(
+ * @Constraint(
  *   id = "CommentName",
  *   label = @Translation("Comment author name", context = "Validation")
  * )
diff --git a/core/modules/link/src/Plugin/Validation/Constraint/LinkTypeConstraint.php b/core/modules/link/src/Plugin/Validation/Constraint/LinkTypeConstraint.php
index 89ff6da..891f386 100644
--- a/core/modules/link/src/Plugin/Validation/Constraint/LinkTypeConstraint.php
+++ b/core/modules/link/src/Plugin/Validation/Constraint/LinkTypeConstraint.php
@@ -15,7 +15,7 @@
 /**
  * Validation constraint for links receiving data allowed by its settings.
  *
- * @Plugin(
+ * @Constraint(
  *   id = "LinkType",
  *   label = @Translation("Link data valid for link type.", context = "Validation"),
  * )