error using PHP file_get_contents to call list_folder api

any examples available using the PHP file_get_contents function to call the files/list_folder api? 

( I am able to use curl from PHP to call the dropbox apis. But my code fails on one PHP server but works on another. Would like to see if file_get_contents will work. )

 

Here is my code.  There error I am getting is "failed to open stream: HTTP request failed! HTTP/1.1 400 Bad Request "

function listFolder( $token )
{
  $text = "{\"path\": \"\",\"recursive\": false,\"include_media_info\": false,\"include_deleted\": false,\"include_has_explicit_shared_members\": false,\"include_mounted_folders\": true}" ;
  echo $text . '<br>' ;

  $postdata = http_build_query(
    array(
        'data' => $text)) ;

  $opts = array(
      'http' => array(
                'method'  => 'POST',
                'header'  => array('Authorization: Bearer ' . $token,
                                   'Content-Type: application/json'),
                'content' => $postdata),
      'ssl' => array(
                "verify_peer"=>false,
                "verify_peer_name"=>false)
  );

  $context  = stream_context_create($opts);

  $result = file_get_contents('https://api.dropboxapi.com/2/files/list_folder', false, $context);
}