Having problem with registration POST

Hello, I am trying to use your plugin. I am creating a POST request for user registration. I am sending user details as JSON array. Now the plugin response with ‘You must include ‘username’ var in your request’. The only way I can get around this is by sending the details in query parameter (username, display_name). Then it works even if I send a blank body. So essentially it is a GET request URL, but getting send with POST method. Is that right? Thanks.