public void add(final LinkData linkData) {
        Objects.requireNonNull(linkData, "linkData");

        if (!this.equals(linkData)) {
            throw new IllegalArgumentException("Can't merge with different link.");
        }
        final LinkCallDataMap target = linkData.linkCallDataMap;
        this.linkCallDataMap.addLinkDataMap(target);
    }
@param hostname
           host name or endpoint
@param slot
@param count
web/src/main/java/com/navercorp/pinpoint/web/applicationmap/rawdata/LinkData.java