namespace AWSTestLambda.Controllers
{
    [Route("api/v1/[Controller]")]
    public class ItemsController : RpcController
    {
        public String Test(int id)
        {
            return "testing";
        }
    }
}

{
    "jsonrpc": "2.0",
    "method": "Get",
    "params": {
        "id": 1234
    },
    "id": ""
}

{
    "id": "",
    "jsonrpc": "2.0",
    "error": {
        "code": -32601,
        "message": "No methods matched request.",
        "data": null
    }
}