class DefaultHttp2ConnectionEncoder implements Http2ConnectionEncoder {

    @Override
    public ChannelFuture writeData(final ChannelHandlerContext ctx, final int streamId, ByteBuf data, int padding,
            final boolean endOfStream, ChannelPromise promise) {
        final Http2Stream stream;
        try {
            stream = requireStream(streamId);

            // Verify that the stream is in the appropriate state for sending DATA frames.
            switch (stream.state()) {
                case OPEN:
                case HALF_CLOSED_REMOTE:
                    // Allowed sending DATA frames in these states.
                    break;
                default:
                    throw new IllegalStateException("Stream " + stream.id() + " in unexpected state " + stream.state());
            }
        } catch (Throwable e) {
            data.release();
            return promise.setFailure(e);
        }

        // Hand control of the frame to the flow controller.
        flowController().addFlowControlled(stream,
                new FlowControlledData(stream, data, padding, endOfStream, promise));
        return promise;
    }

    public  DefaultHttp2ConnectionEncoder(Http2Connection connection, Http2FrameWriter frameWriter);

}