private LinkHistogramSummary createEmptyLinkHistogramSummary(LinkDirection direction, Application fromApplication, Application toApplication, Range range) {
        Node fromNode = new Node(fromApplication);
        Node toNode = new Node(toApplication);
        Link emptyLink = new Link(direction, fromNode, toNode, range);
        return new LinkHistogramSummary(emptyLink);
    }
@author HyunGil Jeong
@author jaehong.kim
web/src/main/java/com/navercorp/pinpoint/web/applicationmap/service/ResponseTimeHistogramServiceImpl.java