Given I am on : /api/ezp/v2/user/sessions an calling the rest-Api
then I want to see following response on posting empty body.
{
    "ErrorMessage": {
        "_media-type": "application\/vnd.ez.api.ErrorMessage+json",
        "errorCode": 422,
        "errorMessage": "Unprocessable Entity",
        "errorDescription": "Request Body is empty"
    }
}

instead of current response:

{   "ErrorMessage":{      "_media-type":"application\/vnd.ez.api.ErrorMessage+json",
      "errorCode":400,
      "errorMessage":"Bad Request",
      "errorDescription":"An error occured while decoding the JSON       input:\nSyntax error\nInput JSON:\n\n"
   }
}