public static Http2MultiplexCodecBuilder forServer(ChannelHandler childHandler) {
        return new Http2MultiplexCodecBuilder(true, childHandler);
    }
@Test
    public void testUnsharableHandler() {
        assertThrows(IllegalArgumentException.class, new Executable() {
            @Override
            public void execute() throws Throwable {
                Http2MultiplexCodecBuilder.forServer(new UnsharableChannelHandler());
            }
        });
    }