Netty NotFoundHandler does not work well with HttpContentCompressor

[yanns]

when using HttpContentCompressor to compress the http responses, and when the handler NotFoundHandler is used, then the HttpContentCompressor does not really know how to handle this http response.
The response contains content-encoding: gzip although there is no body.
According to https://datatracker.ietf.org/doc/html/rfc7231#section-3.1.2.2, it should not do it.

When changing the io.netty.handler.codec.http.DefaultHttpResponse into a io.netty.handler.codec.http.DefaultFullHttpResponse, the issue disappears. I don't know if it's an issue on netty side.

It's a small change for unfiltered, and would help users to change that.