--- /dev/null
+<?php
+
+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|null
+ * The owner user ID, or NULL in case the user ID field has not been set on
+ * the entity.
+ */
+ public function getOwnerId();
+
+ /**
+ * Sets the entity owner's user ID.
+ *
+ * @param int $uid
+ * The owner user id.
+ *
+ * @return $this
+ */
+ public function setOwnerId($uid);
+
+}