private void readUnknownFrame(ChannelHandlerContext ctx, ByteBuf payload,
            Http2FrameListener listener) throws Http2Exception {
        listener.onUnknownFrame(ctx, frameType, streamId, flags, payload);
    }
@Test
    public void readUnknownFrame() throws Http2Exception {
        ByteBuf input = Unpooled.buffer();
        ByteBuf payload = Unpooled.buffer();
        try {
            payload.writeByte(1);

            writeFrameHeader(input, payload.readableBytes(), (byte) 0xff, new Http2Flags(), 0);
            input.writeBytes(payload);
            frameReader.readFrame(ctx, input, listener);

            verify(listener).onUnknownFrame(
                    ctx, (byte) 0xff, 0, new Http2Flags(), payload.slice(0, 1));
        } finally {
            payload.release();
            input.release();
        }
    }