* GET /prod/ HTTP/1.1
     * Key: value1,value2,value3
     * Foo: Bar

        APIGatewayProxyRequestEvent request = new APIGatewayProxyRequestEvent()
        Map<String, String> headers = new HashMap<>()
        headers.put("Foo", "Bar")
        headers.put("Key", "value1,value2,value3")
        request.setHeaders(headers)
        Map<String, List<String>> multiValueHeaders = new HashMap<>()
        multiValueHeaders.put("Key", Arrays.asList("value1", "value2", "value3"))
        multiValueHeaders.put("Foo", Collections.singletonList("Bar"))
        request.setMultiValueHeaders(multiValueHeaders)