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

core/lib/Drupal/Component/Uuid/UuidInterface.php

@@ -0,0 +1,22 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Component\Uuid\UuidInterface.
+ */
+
+namespace Drupal\Component\Uuid;
+
+/**
+ * Interface that defines a UUID backend.
+ */
+interface UuidInterface {
+
+  /**
+   * Generates a Universally Unique IDentifier (UUID).
+   *
+   * @return
+   *   A 16 byte integer represented as a hex string formatted with 4 hyphens.
+   */
+  public function generate();
+}