无法打开流：HTTP请求失败！ 找不到HTTP / 1.1 404

I am calling rest api using file_get_contents with basic authentication. This request is working fine in Postman, but it is responding 404 with file_get_contents.

$options = array(
    'http' => array(
        'method'  => 'POST',
        'content' => json_encode($data),
        'header'  => "Content-Type: application/json
Authorization: Basic " . base64_encode('username:password') . "
",
    ),
);

$context = stream_context_create($options);
$result = file_get_contents($url, false, $context);