boolean containsKey(int key, int hash) {
      if (count != 0) { // read-volatile
        HashEntry<V> e = getFirst(hash);
        while (e != null) {
          if (e.hash == hash && key == e.key) {
            return true;
          }
          e = e.next;
        }
      }
      return false;
    }
Reads value field of an entry under lock. Called if value field ever appears to be null. This
is possible only if a compiler happens to reorder a HashEntry initialization with its table
assignment, which is legal under memory model but is not known to ever occur.
geode-core/src/main/java/org/apache/geode/internal/ObjIdConcurrentMap.java