@Override
    public boolean equals(Object o1, Object o2) {
      if (o1 == null && o2 == null) {
        return true;
      }
      if (o1 == null || o2 == null) {
        return false;
      }
      return o1.equals(o2);
    }
Reconstitute the <tt>HashMap</tt> instance from a stream (i.e., deserialize it).
geode-core/src/main/java/org/apache/geode/cache/query/internal/ObjectIntHashMap.java