Wrong Marshalling when Entity is `Optional`

When completing a route with a Java Optional the output is not the one I would expect:

Expected Behavior

• If Optional[T] is empty: completed with an empty Entity
• If Optional[T] is not empty: completed with proper marshalling of T

Actual Behavior

• If Optional[T] is empty: completed with {"present": false}
• If Optional[T] is not empty: completed with {"present": true}

I have a gist where one can reproduce this: https://gist.github.com/jlprat/5e1c27ce4b912e0a3eb0ad56237246d7