Function encode_request_frame_with_buffer 

pub fn encode_request_frame_with_buffer<F>(
    frame: &mut BytesMut,
    spec: RequestFrameSpec<'_>,
    write_body: F,
) -> Result<()>
where
    F: FnOnce(&mut BytesMut) -> Result<()>,

Encode a Kafka request frame into a caller-supplied buffer.