diff --git a/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkFormController.php b/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkFormController.php
index 9506602..6e75628 100644
--- a/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkFormController.php
+++ b/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkFormController.php
@@ -8,12 +8,12 @@
 namespace Drupal\menu_link;
 
 use Drupal\Core\Entity\EntityInterface;
-use Drupal\Core\Entity\EntityFormController;
+use Drupal\Core\Entity\EntityFormControllerNG;
 
 /**
  * Form controller for the node edit forms.
  */
-class MenuLinkFormController extends EntityFormController {
+class MenuLinkFormController extends EntityFormControllerNG {
 
   /**
    * Overrides EntityFormController::form().
@@ -42,7 +42,7 @@ public function form(array $form, array &$form_state, EntityInterface $menu_link
       '#required' => TRUE,
     );
     foreach (array('link_path', 'mlid', 'module', 'has_children', 'options') as $key) {
-      $form[$key] = array('#type' => 'value', '#value' => $menu_link->{$key});
+      $form[$key] = array('#type' => 'value', '#value' => $menu_link->{$key}->value);
     }
     // Any item created or edited via this interface is considered "customized".
     $form['customized'] = array('#type' => 'value', '#value' => 1);
diff --git a/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkStorageController.php b/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkStorageController.php
index 5180b3e..3558521 100644
--- a/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkStorageController.php
+++ b/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkStorageController.php
@@ -7,7 +7,7 @@
 
 namespace Drupal\menu_link;
 
-use Drupal\Core\Entity\DatabaseStorageController;
+use Drupal\Core\Entity\DatabaseStorageControllerNG;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\EntityStorageException;
 
@@ -17,7 +17,7 @@
  * This extends the Drupal\entity\DatabaseStorageController class, adding
  * required special handling for menu_link entities.
  */
-class MenuLinkStorageController extends DatabaseStorageController {
+class MenuLinkStorageController extends DatabaseStorageControllerNG {
 
   /**
    * Indicates whether the delete operation should re-parent children items.
@@ -65,15 +65,16 @@ protected function attachLoad(&$menu_links, $load_revision = FALSE) {
     $routes = array();
 
     foreach ($menu_links as &$menu_link) {
+      // @todo: what to do about options?
       $menu_link->options = unserialize($menu_link->options);
 
       // Use the weight property from the menu link.
-      $menu_link->router_item['weight'] = $menu_link->weight;
+      $menu_link->router_item['weight'] = $menu_link->weight->value;
 
       // For all links that have an associated route, load the route object now
       // and save it on the object. That way we avoid a select N+1 problem later.
-      if ($menu_link->route_name) {
-        $routes[$menu_link->id()] = $menu_link->route_name;
+      if ($menu_link->route_name->value) {
+        $routes[$menu_link->id()] = $menu_link->route_name->value;
       }
     }
 
@@ -105,7 +106,7 @@ public function save(EntityInterface $entity) {
       }
 
       if ($entity->isNew()) {
-        $entity->mlid = db_insert($this->entityInfo['base_table'])->fields(array('menu_name' => 'tools'))->execute();
+        $entity->mlid->value = db_insert($this->entityInfo['base_table'])->fields(array('menu_name' => 'tools'))->execute();
         $entity->enforceIsNew();
       }
 
@@ -159,58 +160,58 @@ public function save(EntityInterface $entity) {
   protected function preSave(EntityInterface $entity) {
     // This is the easiest way to handle the unique internal path '<front>',
     // since a path marked as external does not need to match a router path.
-    $entity->external = (url_is_external($entity->link_path) || $entity->link_path == '<front>') ? 1 : 0;
+    $entity->external->value = (url_is_external($entity->link_path->value) || $entity->link_path->value == '<front>') ? 1 : 0;
 
     // Try to find a parent link. If found, assign it and derive its menu.
     $parent_candidates = !empty($entity->parentCandidates) ? $entity->parentCandidates : array();
     $parent = $this->findParent($entity, $parent_candidates);
     if ($parent) {
-      $entity->plid = $parent->id();
-      $entity->menu_name = $parent->menu_name;
+      $entity->plid->value = $parent->id();
+      $entity->menu_name->value = $parent->menu_name->value;
     }
     // If no corresponding parent link was found, move the link to the top-level.
     else {
-      $entity->plid = 0;
+      $entity->plid->value = 0;
     }
 
     // Directly fill parents for top-level links.
-    if ($entity->plid == 0) {
+    if ($entity->plid->value == 0) {
       $entity->p1 = $entity->id();
       for ($i = 2; $i <= MENU_MAX_DEPTH; $i++) {
         $parent_property = "p$i";
         $entity->$parent_property = 0;
       }
-      $entity->depth = 1;
+      $entity->depth->value = 1;
     }
     // Otherwise, ensure that this link's depth is not beyond the maximum depth
     // and fill parents based on the parent link.
     else {
-      if ($entity->has_children && $entity->original) {
+      if ($entity->has_children->value && $entity->original) {
         $limit = MENU_MAX_DEPTH - $this->findChildrenRelativeDepth($entity->original) - 1;
       }
       else {
         $limit = MENU_MAX_DEPTH - 1;
       }
-      if ($parent->depth > $limit) {
+      if ($parent->depth->value > $limit) {
         return FALSE;
       }
-      $entity->depth = $parent->depth + 1;
+      $entity->depth->value = $parent->depth->value + 1;
       $this->setParents($entity, $parent);
     }
 
     // Need to check both plid and menu_name, since plid can be 0 in any menu.
-    if (isset($entity->original) && ($entity->plid != $entity->original->plid || $entity->menu_name != $entity->original->menu_name)) {
+    if (isset($entity->original) && ($entity->plid->value != $entity->original->plid->value || $entity->menu_name->value != $entity->original->menu_name->value)) {
       $this->moveChildren($entity, $entity->original);
     }
     // Find the router_path.
-    if (empty($entity->router_path) || empty($entity->original) || (isset($entity->original) && $entity->original->link_path != $entity->link_path)) {
-      if ($entity->external) {
-        $entity->router_path = '';
+    if (empty($entity->router_path->value) || empty($entity->original) || (isset($entity->original) && $entity->original->link_path->value != $entity->link_path->value)) {
+      if ($entity->external->value) {
+        $entity->router_path->value = '';
       }
       else {
         // Find the router path which will serve this path.
-        $entity->parts = explode('/', $entity->link_path, MENU_MAX_PARTS);
-        $entity->router_path = _menu_find_router_path($entity->link_path);
+        $entity->parts = explode('/', $entity->link_path->value, MENU_MAX_PARTS);
+        $entity->router_path->value = _menu_find_router_path($entity->link_path->value);
       }
     }
   }
@@ -222,9 +223,9 @@ function postSave(EntityInterface $entity, $update) {
     // Check the has_children status of the parent.
     $this->updateParentalStatus($entity);
 
-    menu_cache_clear($entity->menu_name);
-    if (isset($entity->original) && $entity->menu_name != $entity->original->menu_name) {
-      menu_cache_clear($entity->original->menu_name);
+    menu_cache_clear($entity->menu_name->value);
+    if (isset($entity->original) && $entity->menu_name->value != $entity->original->menu_name->value) {
+      menu_cache_clear($entity->original->menu_name->value);
     }
 
     // Now clear the cache.
@@ -252,10 +253,10 @@ protected function preDelete($entities) {
 
     foreach ($entities as $entity) {
       // Children get re-attached to the item's parent.
-      if ($entity->has_children) {
-        $children = $this->loadByProperties(array('plid' => $entity->plid));
+      if ($entity->has_children->value) {
+        $children = $this->loadByProperties(array('plid' => $entity->plid->value));
         foreach ($children as $child) {
-          $child->plid = $entity->plid;
+          $child->plid->value = $entity->plid->value;
           $this->save($child);
         }
       }
@@ -274,8 +275,8 @@ protected function postDelete($entities) {
       }
 
       // Store all menu names for which we need to clear the cache.
-      if (!isset($affected_menus[$entity->menu_name])) {
-        $affected_menus[$entity->menu_name] = $entity->menu_name;
+      if (!isset($affected_menus[$entity->menu_name->value])) {
+        $affected_menus[$entity->menu_name->value] = $entity->menu_name->value;
       }
     }
 
@@ -347,13 +348,13 @@ public function loadModuleAdminTasks() {
    */
   protected function updateParentalStatus(EntityInterface $entity, $exclude = FALSE) {
     // If plid == 0, there is nothing to update.
-    if ($entity->plid) {
+    if ($entity->plid->value) {
       // Check if at least one visible child exists in the table.
       $query = entity_query($this->entityType);
       $query
-        ->condition('menu_name', $entity->menu_name)
+        ->condition('menu_name', $entity->menu_name->value)
         ->condition('hidden', 0)
-        ->condition('plid', $entity->plid)
+        ->condition('plid', $entity->plid->value)
         ->count();
 
       if ($exclude) {
@@ -363,7 +364,7 @@ protected function updateParentalStatus(EntityInterface $entity, $exclude = FALS
       $parent_has_children = ((bool) $query->execute()) ? 1 : 0;
       db_update('menu_links')
         ->fields(array('has_children' => $parent_has_children))
-        ->condition('mlid', $entity->plid)
+        ->condition('mlid', $entity->plid->value)
         ->execute();
     }
   }
@@ -392,21 +393,21 @@ protected function findParent(EntityInterface $entity, array $parent_candidates
     $parent = FALSE;
 
     // This item is explicitely top-level, skip the rest of the parenting.
-    if (isset($entity->plid) && empty($entity->plid)) {
+    if (isset($entity->plid->value) && empty($entity->plid->value)) {
       return $parent;
     }
 
     // If we have a parent link ID, try to use that.
     $candidates = array();
-    if (isset($entity->plid)) {
-      $candidates[] = $entity->plid;
+    if (isset($entity->plid->value)) {
+      $candidates[] = $entity->plid->value;
     }
 
     // Else, if we have a link hierarchy try to find a valid parent in there.
-    if (!empty($entity->depth) && $entity->depth > 1) {
-      for ($depth = $entity->depth - 1; $depth >= 1; $depth--) {
+    if (!empty($entity->depth->value) && $entity->depth->value > 1) {
+      for ($depth = $entity->depth->value - 1; $depth >= 1; $depth--) {
         $parent_property = "p$depth";
-        $candidates[] = $entity->$parent_property;
+        $candidates[] = $entity->$parent_property->value;
       }
     }
 
@@ -426,9 +427,9 @@ protected function findParent(EntityInterface $entity, array $parent_candidates
     // If everything else failed, try to derive the parent from the path
     // hierarchy. This only makes sense for links derived from menu router
     // items (ie. from hook_menu()).
-    if ($entity->module == 'system') {
+    if ($entity->module->value == 'system') {
       // Find the parent - it must be unique.
-      $parent_path = $entity->link_path;
+      $parent_path = $entity->link_path->value;
       do {
         $parent = FALSE;
         $parent_path = substr($parent_path, 0, strrpos($parent_path, '/'));
@@ -439,7 +440,7 @@ protected function findParent(EntityInterface $entity, array $parent_candidates
           ->condition('module', 'system')
           // We always respect the link's 'menu_name'; inheritance for router
           // items is ensured in _menu_router_build().
-          ->condition('menu_name', $entity->menu_name)
+          ->condition('menu_name', $entity->menu_name->value)
           ->condition('link_path', $parent_path);
 
         $result = $query->execute();
@@ -464,7 +465,7 @@ protected function findParent(EntityInterface $entity, array $parent_candidates
    */
   protected function setParents(EntityInterface $entity, EntityInterface $parent) {
     $i = 1;
-    while ($i < $entity->depth) {
+    while ($i < $entity->depth->value) {
       $p = 'p' . $i++;
       $entity->{$p} = $parent->{$p};
     }
@@ -494,7 +495,7 @@ public function findChildrenRelativeDepth(EntityInterface $entity) {
     // make sense to convert to EFQ?
     $query = db_select('menu_links');
     $query->addField('menu_links', 'depth');
-    $query->condition('menu_name', $entity->menu_name);
+    $query->condition('menu_name', $entity->menu_name->value);
     $query->orderBy('depth', 'DESC');
     $query->range(0, 1);
 
@@ -507,7 +508,7 @@ public function findChildrenRelativeDepth(EntityInterface $entity) {
 
     $max_depth = $query->execute()->fetchField();
 
-    return ($max_depth > $entity->depth) ? $max_depth - $entity->depth : 0;
+    return ($max_depth > $entity->depth->value) ? $max_depth - $entity->depth->value : 0;
   }
 
   /**
@@ -522,14 +523,14 @@ public function findChildrenRelativeDepth(EntityInterface $entity) {
   protected function moveChildren(EntityInterface $entity) {
     $query = db_update($this->entityInfo['base_table']);
 
-    $query->fields(array('menu_name' => $entity->menu_name));
+    $query->fields(array('menu_name' => $entity->menu_name->value));
 
     $p = 'p1';
     $expressions = array();
-    for ($i = 1; $i <= $entity->depth; $p = 'p' . ++$i) {
+    for ($i = 1; $i <= $entity->depth->value; $p = 'p' . ++$i) {
       $expressions[] = array($p, ":p_$i", array(":p_$i" => $entity->{$p}));
     }
-    $j = $entity->original->depth + 1;
+    $j = $entity->original->depth->value + 1;
     while ($i <= MENU_MAX_DEPTH && $j <= MENU_MAX_DEPTH) {
       $expressions[] = array('p' . $i++, 'p' . $j++, array());
     }
@@ -537,7 +538,7 @@ protected function moveChildren(EntityInterface $entity) {
       $expressions[] = array('p' . $i++, 0, array());
     }
 
-    $shift = $entity->depth - $entity->original->depth;
+    $shift = $entity->depth->value - $entity->original->depth->value;
     if ($shift > 0) {
       // The order of expressions must be reversed so the new values don't
       // overwrite the old ones before they can be used because "Single-table
@@ -550,7 +551,7 @@ protected function moveChildren(EntityInterface $entity) {
     }
 
     $query->expression('depth', 'depth + :depth', array(':depth' => $shift));
-    $query->condition('menu_name', $entity->original->menu_name);
+    $query->condition('menu_name', $entity->original->menu_name->value);
     $p = 'p1';
     for ($i = 1; $i <= MENU_MAX_DEPTH && $entity->original->{$p}; $p = 'p' . ++$i) {
       $query->condition($p, $entity->original->{$p});
@@ -575,4 +576,146 @@ public function countMenuLinks($menu_name) {
       ->count();
     return $query->execute();
   }
+
+  /**
+   * Implements \Drupal\Core\Entity\DatabaseStorageControllerNG::basePropertyDefinitions().
+   */
+  public function baseFieldDefinitions() {
+    $properties['menu_name'] = array(
+      'label' => t('The link\'s menu name.'),
+      'description' => t('The menu link UUID.'),
+      'type' => 'string_field',
+    );
+    $properties['mlid'] = array(
+      'label' => t('ID'),
+      'description' => t('The menu link ID.'),
+      'type' => 'integer_field',
+      'read-only' => TRUE,
+    );
+    $properties['uuid'] = array(
+      'label' => t('UUID'),
+      'description' => t('The menu link UUID.'),
+      'type' => 'string_field',
+    );
+    $properties['plid'] = array(
+      'label' => t('Parent ID'),
+      'description' => t('The parent link ID if this is a child link.'),
+      'type' => 'entity_reference_field',
+      'settings' => array('target_type' => 'menu_link'),
+    );
+    $properties['link_path'] = array(
+      'label' => t('The menu link path'),
+      'description' => t('The Drupal path or external path this link points to.'),
+      'type' => 'string_field',
+    );
+    $properties['router_path'] = array(
+      'label' => t('The menu link router path'),
+      'description' => t('For links corresponding to a Drupal path (external = 0), this connects the link to a {menu_router}.path for joins.'),
+      'type' => 'string_field',
+    );
+    $properties['link_title'] = array(
+      'label' => t('The menu link title'),
+      'description' => t('The entity label.'),
+      'type' => 'string_field',
+    );
+    // @todo: how to deal with 'options'??
+    $properties['module'] = array(
+      'label' => t('The menu link module'),
+      'description' => t('The name of the module that generated this link.'),
+      'type' => 'string_field',
+    );
+    $properties['hidden'] = array(
+      'label' => t('Hidden flag'),
+      'description' => t('A flag for whether the link should be rendered in menus.'),
+      'type' => 'boolean_field',
+    );
+    $properties['external'] = array(
+      'label' => t('External flag'),
+      'description' => t('A flag to indicate if the link points to a full URL starting with a protocol, like http:// (1 = external, 0 = internal.)'),
+      'type' => 'boolean_field',
+    );
+    $properties['has_children'] = array(
+      'label' => t('Has children flag'),
+      'description' => t('A flag indicating whether any links have this link as a parent.'),
+      'type' => 'boolean_field',
+    );
+    $properties['expanded'] = array(
+      'label' => t('Expanded flag'),
+      'description' => t('A flag for whether this link should be rendered as expanded in menus.'),
+      'type' => 'boolean_field',
+    );
+    $properties['weight'] = array(
+      'label' => t('Weight'),
+      'description' => t('Link weight among links in the same menu at the same depth.'),
+      'type' => 'integer_field',
+    );
+    $properties['depth'] = array(
+      'label' => t('Depth'),
+      'description' => t('The depth relative to the top level.'),
+      'type' => 'integer_field',
+      'read-only' => TRUE,
+    );
+    $properties['customized'] = array(
+      'label' => t('Customized flag'),
+      'description' => t('A flag to indicate that the user has manually created or edited the link.'),
+      'type' => 'boolean_field',
+    );
+    $properties['p1'] = array(
+      'label' => t('Path entity 1'),
+      'description' => t('The first entity in the materialized path.'),
+      'type' => 'entity_reference_field',
+    );
+    $properties['p2'] = array(
+      'label' => t('Path entity 2'),
+      'description' => t('The second entity in the materialized path.'),
+      'type' => 'entity_reference_field',
+    );
+    $properties['p3'] = array(
+      'label' => t('Path entity 3'),
+      'description' => t('The third entity in the materialized path.'),
+      'type' => 'entity_reference_field',
+    );
+    $properties['p4'] = array(
+      'label' => t('Path entity 4'),
+      'description' => t('The fourth entity in the materialized path.'),
+      'type' => 'entity_reference_field',
+    );
+    $properties['p5'] = array(
+      'label' => t('Path entity 5'),
+      'description' => t('The fifth entity in the materialized path.'),
+      'type' => 'entity_reference_field',
+    );
+    $properties['p6'] = array(
+      'label' => t('Path entity 6'),
+      'description' => t('The sixth entity in the materialized path.'),
+      'type' => 'entity_reference_field',
+    );
+    $properties['p7'] = array(
+      'label' => t('Path entity 7'),
+      'description' => t('The seventh entity in the materialized path.'),
+      'type' => 'entity_reference_field',
+    );
+    $properties['p8'] = array(
+      'label' => t('Path entity 8'),
+      'description' => t('The eighth entity in the materialized path.'),
+      'type' => 'entity_reference_field',
+    );
+    $properties['p9'] = array(
+      'label' => t('Path entity 9'),
+      'description' => t('The ninth entity in the materialized path.'),
+      'type' => 'entity_reference_field',
+    );
+    $properties['updated'] = array(
+      'label' => t('Updated'),
+      'description' => t('The menu link modification timestamp.'),
+      'type' => 'integer_field',
+    );
+    $properties['route_name'] = array(
+      'label' => t('Route name'),
+      'description' => t('The name of the route associated with this menu link, if any.'),
+      'type' => 'string_field',
+    );
+
+    return $properties;
+  }
 }
diff --git a/core/modules/menu_link/lib/Drupal/menu_link/Plugin/Core/Entity/MenuLink.php b/core/modules/menu_link/lib/Drupal/menu_link/Plugin/Core/Entity/MenuLink.php
index ce3911d..0166a7b 100644
--- a/core/modules/menu_link/lib/Drupal/menu_link/Plugin/Core/Entity/MenuLink.php
+++ b/core/modules/menu_link/lib/Drupal/menu_link/Plugin/Core/Entity/MenuLink.php
@@ -12,7 +12,7 @@
 use Drupal\Component\Annotation\Plugin;
 use Drupal\Core\Annotation\Translation;
 use Drupal\Core\Entity\ContentEntityInterface;
-use Drupal\Core\Entity\Entity;
+use Drupal\Core\Entity\EntityNG;
 
 /**
  * Defines the menu link entity class.
@@ -41,40 +41,40 @@
  *   }
  * )
  */
-class MenuLink extends Entity implements \ArrayAccess, ContentEntityInterface {
+class MenuLink extends EntityNG implements \ArrayAccess, ContentEntityInterface {
 
   /**
    * The link's menu name.
    *
-   * @var string
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
-  public $menu_name = 'tools';
+  public $menu_name;
 
   /**
    * The menu link ID.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $mlid;
 
   /**
    * The menu link UUID.
    *
-   * @var string
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $uuid;
 
   /**
    * The parent link ID.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $plid;
 
   /**
    * The Drupal path or external path this link points to.
    *
-   * @var string
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $link_path;
 
@@ -82,89 +82,89 @@ class MenuLink extends Entity implements \ArrayAccess, ContentEntityInterface {
    * For links corresponding to a Drupal path (external = 0), this connects the
    * link to a {menu_router}.path for joins.
    *
-   * @var string
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $router_path;
 
   /**
    * The entity label.
    *
-   * @var string
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
-  public $link_title = '';
+  public $link_title;
 
   /**
    * A serialized array of options to be passed to the url() or l() function,
    * such as a query string or HTML attributes.
    *
-   * @var array
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
-  public $options = array();
+  public $options;
 
   /**
    * The name of the module that generated this link.
    *
-   * @var string
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
-  public $module = 'menu';
+  public $module;
 
   /**
    * A flag for whether the link should be rendered in menus.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
-  public $hidden = 0;
+  public $hidden;
 
   /**
    * A flag to indicate if the link points to a full URL starting with a
    * protocol, like http:// (1 = external, 0 = internal).
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $external;
 
   /**
    * Flag indicating whether any links have this link as a parent.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
-  public $has_children = 0;
+  public $has_children;
 
   /**
    * Flag for whether this link should be rendered as expanded in menus.
    * Expanded links always have their child links displayed, instead of only
    * when the link is in the active trail.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
-  public $expanded = 0;
+  public $expanded;
 
   /**
    * Link weight among links in the same menu at the same depth.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
-  public $weight = 0;
+  public $weight;
 
   /**
    * The depth relative to the top level. A link with plid == 0 will have
    * depth == 1.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $depth;
 
   /**
    * A flag to indicate that the user has manually created or edited the link.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
-  public $customized = 0;
+  public $customized;
 
   /**
    * The first entity ID in the materialized path.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    *
    * @todo Investigate whether the p1, p2, .. pX properties can be moved to a
    * single array property.
@@ -174,70 +174,70 @@ class MenuLink extends Entity implements \ArrayAccess, ContentEntityInterface {
   /**
    * The second entity ID in the materialized path.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $p2;
 
   /**
    * The third entity ID in the materialized path.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $p3;
 
   /**
    * The fourth entity ID in the materialized path.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $p4;
 
   /**
    * The fifth entity ID in the materialized path.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $p5;
 
   /**
    * The sixth entity ID in the materialized path.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $p6;
 
   /**
    * The seventh entity ID in the materialized path.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $p7;
 
   /**
    * The eighth entity ID in the materialized path.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $p8;
 
   /**
    * The ninth entity ID in the materialized path.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $p9;
 
   /**
    * The menu link modification timestamp.
    *
-   * @var int
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
-  public $updated = 0;
+  public $updated;
 
   /**
    * The name of the route associated with this menu link, if any.
    *
-   * @var string
+   * @var \Drupal\Core\Entity\Field\FieldInterface
    */
   public $route_name;
 
@@ -249,14 +249,71 @@ class MenuLink extends Entity implements \ArrayAccess, ContentEntityInterface {
   protected $routeObject;
 
   /**
-   * Overrides Entity::id().
+   * The plain data values of the contained properties.
+   *
+   * Define default values.
+   *
+   * @var array
+   */
+  protected $values = array(
+    'menu_name' => array(LANGUAGE_DEFAULT => array(0 => array('value' => 'tools'))),
+    'link_title' => array(LANGUAGE_DEFAULT => array(0 => array('value' => ''))),
+    // @todo: what to do about 'options'?? It's default is an empty array().
+    'module' => array(LANGUAGE_DEFAULT => array(0 => array('value' => 'menu'))),
+    'hidden' => array(LANGUAGE_DEFAULT => array(0 => array('value' => 0))),
+    'has_childern' => array(LANGUAGE_DEFAULT => array(0 => array('value' => 0))),
+    'expanded' => array(LANGUAGE_DEFAULT => array(0 => array('value' => 0))),
+    'weight' => array(LANGUAGE_DEFAULT => array(0 => array('value' => 0))),
+    'customized' => array(LANGUAGE_DEFAULT => array(0 => array('value' => 0))),
+    'updated' => array(LANGUAGE_DEFAULT => array(0 => array('value' => 0))),
+  );
+
+  /**
+   * Initialize the object. Invoked upon construction and wake up.
+   */
+  protected function init() {
+    parent::init();
+    // We unset all defined properties, so magic getters apply.
+    unset($this->menu_name);
+    unset($this->mlid);
+    unset($this->uuid);
+    unset($this->plid);
+    unset($this->link_path);
+    unset($this->router_path);
+    unset($this->link_title);
+    unset($this->options);
+    unset($this->module);
+    unset($this->hidden);
+    unset($this->external);
+    unset($this->has_children);
+    unset($this->expanded);
+    unset($this->weight);
+    unset($this->depth);
+    unset($this->customized);
+    unset($this->p1);
+    unset($this->p2);
+    unset($this->p3);
+    unset($this->p4);
+    unset($this->p5);
+    unset($this->p6);
+    unset($this->p7);
+    unset($this->p8);
+    unset($this->p9);
+    unset($this->updated);
+    unset($this->route_name);
+  }
+
+  /**
+   * Implements Drupal\Core\Entity\EntityInterface::id().
    */
   public function id() {
-    return $this->mlid;
+    return $this->get('mlid')->value;
   }
 
   /**
    * Overrides Entity::createDuplicate().
+   *
+   * @todo: this needs to change... but how?
    */
   public function createDuplicate() {
     $duplicate = parent::createDuplicate();
@@ -299,6 +356,8 @@ public function setRouteObject(Route $route) {
    *
    * @return \Drupal\Core\Entity\EntityInterface
    *   A menu link entity.
+   *
+   * @todo: how should this be?
    */
   public function reset() {
     // To reset the link to its original values, we need to retrieve its
@@ -311,7 +370,7 @@ public function reset() {
     $new_link = self::buildFromRouterItem($router_item);
     // Merge existing menu link's ID and 'has_children' property.
     foreach (array('mlid', 'has_children') as $key) {
-      $new_link->{$key} = $this->{$key};
+      $new_link->{$key}->value = $this->{$key}->value;
     }
     $new_link->save();
     return $new_link;