public ServerGroupList build() {
            List<ServerGroup> serverGroups = new ArrayList<>();
            for (Map.Entry<String, List<ServerInstance>> entry : map.entrySet()) {
                String hostName = entry.getKey();
                List<ServerInstance> serverInstances = entry.getValue();

                serverGroups.add(new ServerGroup(hostName, null, serverInstances));
            }
            serverGroups.sort(HOST_NAME_COMPARATOR);
            return new ServerGroupList(serverGroups);
        }
@author emeroad
@author netspider
@author minwoo.jung
@author HyunGil Jeong
web/src/main/java/com/navercorp/pinpoint/web/applicationmap/nodes/ServerGroupList.java