diff --git a/core/modules/user/src/EntityOwnerTrait.php b/core/modules/user/src/EntityOwnerTrait.php
new file mode 100644
index 0000000..3ae8e44
--- /dev/null
+++ b/core/modules/user/src/EntityOwnerTrait.php
@@ -0,0 +1,87 @@
+<?php
+
+namespace Drupal\user;
+
+use Drupal\Core\Field\BaseFieldDefinition;
+
+/**
+ * Trait implementing the various methods defined in EntityOwnerInterface.
+ *
+ * @see \Drupal\user\EntityOwnerInterface
+ */
+trait EntityOwnerTrait {
+
+  /**
+   * Defines 'uid' base field definition.
+   *
+   * @return \Drupal\Core\Field\BaseFieldDefinition
+   *   A field definition object.
+   */
+  public static function getOwnerFieldDefinition() {
+    return BaseFieldDefinition::create('entity_reference')
+      ->setLabel(t('Owner'))
+      ->setRevisionable(TRUE)
+      ->setSetting('target_type', 'user')
+      ->setDefaultValueCallback('Drupal\user\EntityOwnerTrait::getDefaultAuthorId');
+  }
+
+  /**
+   * Default value callback for 'uid' base field definition.
+   *
+   * @see ::baseFieldDefinitions()
+   *
+   * @return int
+   *   The user ID.
+   */
+  public static function getDefaultAuthorId() {
+    return \Drupal::currentUser()->id();
+  }
+
+  /**
+   * Returns the entity owner's user entity.
+   *
+   * @return \Drupal\user\UserInterface
+   *   The owner user entity.
+   */
+  public function getOwner() {
+    return $this->get('uid')->entity;
+  }
+
+  /**
+   * Sets the entity owner's user entity.
+   *
+   * @param \Drupal\user\UserInterface $account
+   *   The owner user entity.
+   *
+   * @return $this
+   */
+  public function setOwner(UserInterface $account) {
+    $this->set('uid', $account->id());
+    return $this;
+  }
+
+  /**
+   * Returns the entity owner's user ID.
+   *
+   * @return int|null
+   *   The owner user ID, or NULL in case the user ID field has not been set on
+   *   the entity.
+   */
+  public function getOwnerId() {
+    return $this->get('uid')->target_id;
+  }
+
+  /**
+   * Sets the entity owner's user ID.
+   *
+   * @param int $uid
+   *   The owner user id.
+   *
+   * @return $this
+   */
+  public function setOwnerId($uid) {
+    $this->set('uid', $uid);
+    return $this;
+  }
+
+}