code: public void populateInstanceCountMap(Map<String, AtomicInteger> instanceCountMap) {
          for (Application app : this.getRegisteredApplications()) {
              for (InstanceInfo info : app.getInstancesAsIsFromEureka()) {
                  AtomicInteger instanceCount = instanceCountMap.computeIfAbsent(info.getStatus().name(),
                          k -> new AtomicInteger(0));
                  instanceCount.incrementAndGet();
              }
          }
      }
docs: Populates the provided instance count map. The instance count map is used
  as part of the general app list synchronization mechanism.
  
  @param instanceCountMap
  the map to populate