How to reference sub-flow environment variables in Jsonata?

I’m trying to put a “logbook.log” Action node inside a sub-flow, and want to pass the entity_id and message in through sub-flow environment variables - but I can’t work-out what format to use inside the Jsonata data expression.

An existing logbook write action node might have this in the Data field:
{“name”:“HWS Relay”,“entity_id”:“switch.hws_logbook_entries”,“message”:“Turned On”}

I have 2 Sub-flow environment variables:
LOG_ENTITY
LOG_MESSAGE

How would I change the Jsonata to reference the environment variables instead of the static text?

(I am strictly a “monkey-see, monkey-do” when it comes to Jsonata, and have exhausted the possibilities I can think of for the correct formatting.)

{
  "name": "HWS Relay",
  "entity_id": $env("LOG_ENTITY"),
  "message": $env("LOG_MESSAGE")
}

https://nodered.org/docs/user-guide/environment-variables#jsonata-expressions

thank you very much for your reply. I had found that help reference, but hadn’t switched my Data field from the first format option (moustache ??) to JSON - when I switched it to JSON, all is well ! Thank you again