Drupal Rest client doesn't support superscript chars in request

Hi,
Couldn't create node with superscript chars in title, description etc fields.

Steps to reproduce
1. Send POST request restapi/node with ® or © symbols in title field
{
"type": "product",
"title": "SupTag® Product©",
...
}

Actual result
Response with error returned:
HttpCode 401 : ["Missing required argument node"]

Thanks,
Vitali