Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/user/src/EntityOwnerInterface.php

@@ -0,0 +1,56 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\user\EntityOwnerInterface.
+ */
+
+namespace Drupal\user;
+
+/**
+ * Defines a common interface for entities that have an owner.
+ *
+ * An owner is someone who has primary control over an entity, similar to
+ * owners in Unix file system access. This may or may not be the entity's
+ * original author. The owner may also have less permissions than other users,
+ * such as administrators.
+ */
+interface EntityOwnerInterface {
+
+  /**
+   * Returns the entity owner's user entity.
+   *
+   * @return \Drupal\user\UserInterface
+   *   The owner user entity.
+   */
+  public function getOwner();
+
+  /**
+   * Sets the entity owner's user entity.
+   *
+   * @param \Drupal\user\UserInterface $account
+   *   The owner user entity.
+   *
+   * @return $this
+   */
+  public function setOwner(UserInterface $account);
+
+  /**
+   * Returns the entity owner's user ID.
+   *
+   * @return int
+   *   The owner user ID.
+   */
+  public function getOwnerId();
+
+  /**
+   * Sets the entity owner's user ID.
+   *
+   * @param int $uid
+   *   The owner user id.
+   *
+   * @return $this
+   */
+  public function setOwnerId($uid);
+
+}