diff --git a/lib/Drupal/Component/Plugin/Context/ContextDefinitionInterface.php b/lib/Drupal/Component/Plugin/Context/ContextDefinitionInterface.php
index 16fdc8b..c7b69a0 100644
--- a/lib/Drupal/Component/Plugin/Context/ContextDefinitionInterface.php
+++ b/lib/Drupal/Component/Plugin/Context/ContextDefinitionInterface.php
@@ -150,7 +150,7 @@ public function addConstraint($constraint_name, $options = NULL);
    * Returns a validation constraint.
    *
    * @param string $constraint_name
-   *   The name of the the constraint, i.e. its plugin id.
+   *   The name of the constraint, i.e. its plugin id.
    *
    * @return array
    *   A validation constraint definition which can be used for instantiating a
diff --git a/lib/Drupal/Component/Plugin/Discovery/CachedDiscoveryInterface.php b/lib/Drupal/Component/Plugin/Discovery/CachedDiscoveryInterface.php
index a9d95fc..5f9aa10 100644
--- a/lib/Drupal/Component/Plugin/Discovery/CachedDiscoveryInterface.php
+++ b/lib/Drupal/Component/Plugin/Discovery/CachedDiscoveryInterface.php
@@ -21,4 +21,17 @@ interface CachedDiscoveryInterface extends DiscoveryInterface {
    */
   public function clearCachedDefinitions();
 
+  /**
+   * Disable the use of caches.
+   *
+   * Can be used to ensure that uncached plugin definitions are returned,
+   * without invalidating all cached information.
+   *
+   * This will also remove all local/static caches.
+   *
+   * @param bool $use_caches
+   *   FALSE to not use any caches.
+   */
+  public function useCaches($use_caches = FALSE);
+
 }
diff --git a/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php b/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php
index 5b44bf9..adaaa9c 100644
--- a/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php
+++ b/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php
@@ -37,7 +37,7 @@ public function getDefinition($plugin_id, $exception_on_invalid = TRUE);
    *
    * @return mixed[]
    *   An array of plugin definitions (empty array if no definitions were
-   *   found).
+   *   found). Keys are plugin IDs.
    */
   public function getDefinitions();
 
diff --git a/lib/Drupal/Component/Plugin/LazyPluginCollection.php b/lib/Drupal/Component/Plugin/LazyPluginCollection.php
index 0564da0..f2a9ab0 100644
--- a/lib/Drupal/Component/Plugin/LazyPluginCollection.php
+++ b/lib/Drupal/Component/Plugin/LazyPluginCollection.php
@@ -12,7 +12,7 @@
  *
  * @ingroup plugin_api
  */
-abstract class LazyPluginCollection implements \Iterator, \Countable {
+abstract class LazyPluginCollection implements \IteratorAggregate, \Countable {
 
   /**
    * Stores all instantiated plugins.
@@ -147,46 +147,12 @@ public function removeInstanceId($instance_id) {
     $this->remove($instance_id);
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  public function current() {
-    return $this->get($this->key());
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function next() {
-    next($this->instanceIDs);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function key() {
-    return key($this->instanceIDs);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function valid() {
-    $key = key($this->instanceIDs);
-    // Check the key is valid but also that this key yields a plugin from get().
-    // There can be situations where configuration contains data for a plugin
-    // that cannot be instantiated. In this case, this enables us to skip that
-    // plugin during iteration.
-    // @todo Look at removing when https://drupal.org/node/2080823 has been
-    //   solved.
-    return $key !== NULL && $key !== FALSE && $this->get($key);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function rewind() {
-    reset($this->instanceIDs);
+  public function getIterator() {
+    $instances = [];
+    foreach ($this->getInstanceIds() as $instance_id) {
+      $instances[$instance_id] = $this->get($instance_id);
+    }
+    return new \ArrayIterator($instances);
   }
 
   /**
diff --git a/lib/Drupal/Component/Plugin/composer.json b/lib/Drupal/Component/Plugin/composer.json
index 85caa41..09179e5 100644
--- a/lib/Drupal/Component/Plugin/composer.json
+++ b/lib/Drupal/Component/Plugin/composer.json
@@ -5,13 +5,13 @@
     "homepage": "https://drupal.org/project/drupal",
     "license": "GPL-2.0+",
     "require": {
-        "php": ">=5.4.2"
+        "php": ">=5.4.2",
     },
     "autoload": {
         "psr-0": {
             "Drupal\\Component\\Plugin\\": ""
         }
-    },
+    }
     "suggest": {
         "symfony/validator": "Leveraged in the use of context aware plugins."
     }