Extract response_type and route to the designated handler.

def validate_authorization_request(self, uri, http_method='GET', body=None,
                                       headers=None):
        """Extract response_type and route to the designated handler."""
        request = Request(
            uri, http_method=http_method, body=body, headers=headers)

        request.scopes = utils.scope_to_list(request.scope)

        response_type_handler = self.response_types.get(
            request.response_type, self.default_response_type_handler)
        return response_type_handler.validate_authorization_request(request)