@Override
    public int hashCode() {
      if (compareValues) {
        return (key != null ? key.hashCode() : 0)
            ^ (value != null ? value.hashCode() : 0);
      }
      return System.identityHashCode(key) ^ System.identityHashCode(value);
    }
Returns the hash code value for this map entry. The hash code of a map entry {@code e} is
defined to be:

<pre>
(e.getKey() == null ? 0 : e.getKey().hashCode())
    &circ; (e.getValue() == null ? 0 : e.getValue().hashCode())
</pre>

This ensures that {@code e1.equals(e2)} implies that {@code e1.hashCode()==e2.hashCode()} for
any two Entries {@code e1} and {@code e2}, as required by the general contract of
{@link Object#hashCode}.

@return the hash code value for this map entry
@see #equals
geode-core/src/main/java/org/apache/geode/internal/util/concurrent/CustomEntryConcurrentHashMap.java