private void addEstimate(EstimateMapKey key, LoadEstimateTask task) {
    LoadEstimateTask oldTask;
    oldTask = estimateMap.put(key, task);
    if (oldTask != null) {
      oldTask.cancel();
    }
  }
Add the task to the estimate map at the given key and cancel any old task found
geode-core/src/main/java/org/apache/geode/distributed/internal/LocatorLoadSnapshot.java