public void onGoAwaySent(Channel channel, int lastStreamId, long errorCode, ByteBuf debugData) {
        goAwaySent = true;
        onGoAway(channel, "Sent", lastStreamId, errorCode, debugData);
    }
Returns {@code true} if the connection has received a GOAWAY frame with non-zero error code.
core/src/main/java/com/linecorp/armeria/internal/common/Http2GoAwayHandler.java