Unexpected empty body

[lowcasz]

Encoder should map final fields or even log reason of skip fields.

I'm using in project immutable objects supported by lombok @Value.

I spent a lot lot of time to debug why I have empty body using "consumes = APPLICATION_FORM_URLENCODED_VALUE". All encoders normally encode immutable objects to json, but this one does not. IMO final fields should be serialized. Modifier transient can be used to skip it. It would be nice to have logging of skipped fields and reason of it when FULL logging level is used.