private void updateStateWithSuccessfulReply(int i, Reply r) {
        if (successReply == null || replyIsBetterThanCurrent(r)) {
            setCurrentBestReply(i, r);
        }
    }
Encapsulated logic for merging replies from 1-n related DocumentProtocol messages.
For internal use only. Not multithread safe.
documentapi/src/main/java/com/yahoo/documentapi/messagebus/protocol/ReplyMerger.java