diff --git a/core/lib/Drupal/Core/Entity/Plugin/field/field_type/MapItem.php b/core/lib/Drupal/Core/Entity/Plugin/field/field_type/MapItem.php
deleted file mode 100644
index 3397b2e..0000000
--- a/core/lib/Drupal/Core/Entity/Plugin/field/field_type/MapItem.php
+++ /dev/null
@@ -1,69 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\Core\Entity\Plugin\field\field_type\MapItem.
- */
-
-namespace Drupal\Core\Entity\Plugin\field\field_type;
-
-use Drupal\Core\Entity\Field\FieldItemBase;
-
-/**
- * Defines the 'map' entity field type.
- *
- * @FieldType(
- *   id = "map",
- *   label = @Translation("Map"),
- *   description = @Translation("An entity field containing a map value."),
- *   configurable = FALSE
- * )
- */
-class MapItem extends FieldItemBase {
-
-  /**
-   * Overrides \Drupal\Core\Entity\Field\FieldItemBase::setValue().
-   *
-   * @param array|null $values
-   *   An array of property values.
-   */
-  public function setValue($values, $notify = TRUE) {
-    $this->values = array();
-    if (!isset($values)) {
-      return;
-    }
-
-    if (!is_array($values)) {
-      if ($values instanceof MapItem) {
-        $values = $values->getValue();
-      }
-      else {
-        $values = unserialize($values);
-      }
-    }
-
-    $this->values = $values;
-
-    // Notify the parent of any changes.
-    if ($notify && isset($this->parent)) {
-      $this->parent->onChange($this->name);
-    }
-  }
-
-  public function __get($name) {
-    if (!isset($this->values[$name])) {
-      $this->values[$name] = array();
-    }
-
-    return $this->values[$name];
-  }
-
-  public function __set($name, $value) {
-    if (isset($value)) {
-      $this->values[$name] = $value;
-    }
-    else {
-      unset($this->values[$name]);
-    }
-  }
-}