@Override
  public Object put(Object key, Object value) {
    Entry old = (Entry) map.put(key, new Entry(key, value));
    return old != null ? old.getValue() : null;
  }
This map helps us retrieve the proxy id at the receiver side during GII so that we can retain
the cqlist of a client for an event which already existed at the receiver side.
geode-core/src/main/java/org/apache/geode/internal/cache/ha/HAContainerMap.java