php - DFA Reporting API：如何获取报告文件列表

Question

根据官方文档DCM/DFA Reporting and Trafficking API以这种方式获取 json 格式的报告文件列表：

   $url = "https://www.googleapis.com/dfareporting/v2.3/userprofiles/" . $this->profile_id . "/reports/" . $this->report_id . "/files?key=" . $this->developer_key;

   $opts = array(
        'http' => array(
            'method' => "GET",
            'header' => "content-encoding:  gzip,
                        content-length:  863,
                        content-type:  application/json; charset=UTF-8"
        )
    );

    $context = stream_context_create($opts);

    $response = file_get_contents($url, false, $context);

    var_dump($response);

但是，$response返回错误。我在 API explorer 中玩过它，它在那里工作得很好。有什么想法吗？