Quickstart with Jackson returns wrong message

[dalexandrov]

Generate project with https://helidon.io/starter/3.0.1?flavor=mp&step=4
(Quickstart with Jackson).

Build and run:

curl -X GET http://localhost:8080/greet
{"message":"Hello World!","greeting":null}   

"greeting":null should not be there.

The same quickstart generated with JSON-B returns:

curl -X GET http://localhost:8080/greet
{"message":"Hello World!"}