Add scope entity trait

src/Entities/Traits/ScopeTrait.php

@@ -0,0 +1,28 @@
+<?php
+/**
+ * @author    Andrew Millington <andrew@noexceptions.io>
+ * @copyright Copyright (c) Andrew Millington
+ * @license   http://mit-license.org
+ *
+ * @link      https://github.com/thephpleague/oauth2-server
+ */
+
+namespace League\OAuth2\Server\Entities\Traits;
+
+trait ScopeTrait
+{
+    /**
+     * Serialize the object to the scopes string identifier when using json_encode().
+     *
+     * @return string
+     */
+    public function jsonSerialize()
+    {
+        return $this->getIdentifier();
+    }
+
+    /**
+     * @return string
+     */
+    abstract public function getIdentifier();
+}