@JsonProperty("histogram")
    public Histogram getHistogram() {
        Histogram histogram = new Histogram(agentId.getServiceType());
        histogram.addAll(timeHistogramMap.values());
        return histogram;
    }
to uniquely identify a host from UI, we can use things like hostname, agentId, endpoint, etc
web/src/main/java/com/navercorp/pinpoint/web/applicationmap/rawdata/AgentHistogram.java