guzzle http无法将文件上传到框中

Question

I am trying to upload file using the code below

$response = $client->request('POST', 'https://upload.box.com/api/2.0/files/content', [
    'headers' => [
        'Authorization' => "Bearer {$access_token}",
        'Content-Type' => 'application/x-www-form-urlencoded'
    ], 
    'attributes' => [
        'name' => $file,
        'parent' => ['id',$parent_id],
        'file' => $filePath
    ]
]);

After I run the code on browser, I get this below error

Fatal error: Uncaught exception 'GuzzleHttp\Exception\ClientException' with message 'Client error: POST https://upload.box.com/api/2.0/files/content resulted in a 415 Unsupported Media Type

Any better approach to upload file using GuzzleHttp?.