@Override
  public ClientProxyMembershipID getProxyID(String haRegionName) {
    CacheClientProxy proxy = haRegionNameToProxy.get(haRegionName);
    if (proxy != null) {
      return proxy.getProxyID();
    } else {
      return 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