@staticmethod<EOL><INDENT>def route_not_found(*args):<DEDENT>
response_data = jsonify(ServiceErrorResponses._MISSING_AUTHENTICATION)<EOL>return make_response(response_data, ServiceErrorResponses.HTTP_STATUS_CODE_403)<EOL>
Constructs a Flask Response for when a API Route (path+method) is not found. This is usually
HTTP 404 but with API Gateway this is a HTTP 403 (https://forums.aws.amazon.com/thread.jspa?threadID=2166840)

:return: a Flask Response