private static void addTimer(DistributedSystem system, SystemTimer systemTimer) {
    Set<WeakReference<SystemTimer>> timers;
    synchronized (distributedSystemTimers) {
      timers = distributedSystemTimers.get(system);
      if (timers == null) {
        timers = new HashSet<>();
        distributedSystemTimers.put(system, timers);
      }
    }

    WeakReference<SystemTimer> wr = new WeakReference<>(systemTimer);
    synchronized (timers) {
      timers.add(wr);
    }
  }
Add the given timer is in the given DistributedSystem. Used only by constructors.

@param system DistributedSystem to add the timer to
@param systemTimer timer to add
geode-core/src/main/java/org/apache/geode/internal/SystemTimer.java