void put(Object key, Object o) {
      synchronized (map) {
        map.put(key, o);
      }
    }
A wrapper class whose underlying map gets replaced with a fresh one when QRM thread is
operating on it. This wrapper acts as a means of communication between the QRM thread & the
MapWrapper object contained in the HARegionQueue
geode-core/src/main/java/org/apache/geode/internal/cache/ha/HARegionQueue.java