Javier, did you make any progress here?

I did sit down twice to read the jsonrpc.el code and  understand what I need to do to make the change I hoped to. But unfortunately I can't even say I understood jsonrpc--async-request-1 well enough.Or even, if that is indeed the function we need to change so that we don't seed a params attribute when params is nil. It seems that we are passing the params down in multiple arms?

--
"I object to doing things that computers can do." — Olin Shivers