YouTube API V3 ETag支持失败：内容未更改，但etag更改

Question

我发送带有以下标头的“ playlistItems”请求：

  array(5) {
    [0]=>
    string(29) "Content-Type:application/json"
    [1]=>
    string(153) "Authorization:Bearer [hidden]"
    [2]=>
    string(33) "X-JavaScript-User-Agent:Automator"
    [3]=>
    string(66) "If-Match:"Bdx4f4ps3xCOOo1WZ91nTLkRZ_c/AtpZMDGfwUXtVHbcH_1spJYn8eg""
    [4]=>
    string(71) "If-None-Match:"Bdx4f4ps3xCOOo1WZ91nTLkRZ_c/AtpZMDGfwUXtVHbcH_1spJYn8eg""
  }

网址为：https://www.googleapis.com/youtube/v3/playlistItems?part=id%2Csnippet&playlistId=UUvmF_tzu-eK6FRfMlOp6-Fg

但是我收到的ETag不同，内容没有变化。

Youtube V3真的支持ETag吗？或标题错误？

我不使用任何官方图书馆。我的代码使用PHP和Curl。

$this->execute(
        "playlistItems",
        array("part"=>"id,snippet","playlistId"=>$channelId)
        ,$etag
    );

和

public function execute($source, $options, $etag = null)
{
    if (count($options)==0) {
        $url=$this->base_url.$source;
    } else {
        $vars=array();
        foreach ($options as $key => $value) {
            $vars[]=$key."=".urlencode($value);
        }
        $vars=implode("&", $vars);
        $url=$this->base_url.$source."?".$vars;
    }

    $httpheader=array(
        'Content-Type'=>'application/json',
        'Authorization'=>'Bearer ' . $this->token,
        'X-JavaScript-User-Agent'=>'Automator'
        );
    if ($etag!=null) {
        $httpheader["If-Match"]='"'.$etag.'"';
        $httpheader["If-None-Match"]='"'.$etag.'"';
    }

    $client=new \Conect\Request();
    $request=$client->get($url, array("headers"=>$httpheader));
    $this->etag="";
    if (array_key_exists("ETag", $request->headers_out)) {
        $this->etag=$request->headers_out['ETag'];
    }
    $this->last_request=$request;
    $this->etag=str_replace('"', "", $this->etag);
    $this->etag=trim($this->etag);
    if ($request->code==304) {
        throw new ExceptionNoChange("No changes");
    }
    return $this->response($request->data);
}

“ \ Conect \ Request”部分

if (array_key_exists("headers", $options)) {
    $headers_in=array();
    foreach ($options['headers'] as $key => $value) {
        $headers_in[]=$key.":".$value."";
    }
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers_in);
    $this->headers_in=$headers_in;
}

操作：我发送了一个带有ETag的请求
期望：Http代码304
结果：带有新ETag的Http 200。