pub fn new_empty<B, D>(decoder: D, body: B) -> Self
    where
        B: HttpBody + Send + 'static,
        B::Error: Into<crate::BoxError>,
        D: Decoder<Item = T, Error = Status> + Send + 'static,
    {
        Self::new(decoder, body, Direction::EmptyResponse, None, None)
    }
Create empty response. For creating responses that have no content (headers + trailers only)
tonic/src/codec/decode.rs