The action should return and output a json

[sciabarracom]

the signature of the action pub fn main(input_data: HashMap<String, Value>) -> String

should be instead pub fn main(input_data: HashMap<String, Value>) -> HashMap<String, Value>

the main loop should serialize back the result as a JSON without new lines

Instead of:

{"value":{"name":"Mike"}}
Echo received data: name:"Mike"```

It should be

{"value":{"name":"Mike"}}
Echo received data: name:"Mike"
{"greeting": "Hello Mike"}

Note the output in fd3 must be a json  *without newlines* terminated by a single newline.

This is critical for the actionloop to work.

Normally strings are "hello\nworld", no other newlines should be emitted.