public boolean equals(Object o) {
      if (this == o) {
        return true;
      }
      if (!(o instanceof IdentityWeakReference)) {
        return false;
      }
      IdentityWeakReference wr = (IdentityWeakReference) o;
      Object got = get();
      return (got != null && got == wr.get());
    }
WeakReference where equals and hashCode are based on the referent. More precisely, two objects
are equal if they are identical or if they both have the same non-null referent. The hashCode
is the value the original referent had. Even if the referent is cleared, the hashCode remains.
Thus, objects of this class can be used as keys in hash-based maps and sets.
geode-core/src/main/java/org/apache/geode/pdx/internal/WeakConcurrentIdentityHashMap.java