private static void OnHeader(IHttpHeadersSink sink, object?state, ulong headerNameIndex, ReadOnlySpan <byte> headerValue, HttpHeaderFlags flags)
        {
            PreparedHeader v = GetHeaderForIndex(headerNameIndex);

            OnHeader(sink, state, v._name._http2Encoded, headerValue, flags);
        }
        private static void OnHeader(IHttpHeadersSink sink, object?state, ReadOnlySpan <byte> headerName, ReadOnlySpan <byte> headerValue, HttpHeaderFlags flags)
        {
            if (headerName.Length > 1 && headerName[0] == ':')
            {
                // TODO: check for pseudo headers.
            }

            sink.OnHeader(state, headerName, headerValue, flags);
        }