Move plugin files to a subfolder

[MAILPOET-3988]

mailpoet/lib/API/JSON/SuccessResponse.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace MailPoet\API\JSON;
+
+class SuccessResponse extends Response {
+  public $data;
+
+  public function __construct(
+    $data = [],
+    $meta = [],
+    $status = self::STATUS_OK
+  ) {
+    parent::__construct($status, $meta);
+    $this->data = $data;
+  }
+
+  public function getData() {
+    if ($this->data === null) return [];
+
+    return [
+      'data' => $this->data,
+    ];
+  }
+}