public boolean equals(Object obj) {
      if (obj instanceof Key) {
        return key.equals(((Key) obj).key);
      } else {
        return false;
      }
    }
This class makes sure that instantatiors are persisted to disk and can be recovered.
geode-core/src/integrationTest/java/org/apache/geode/DiskInstantiatorsJUnitTest.java