@Override
  public int sizeof(Object o) {
    if (o instanceof Integer) {
      return 5;
    } else if (o instanceof TestNonSizerObject) {
      return ((TestNonSizerObject) o).getTestString().length();
    } else if (o instanceof CachedDeserializable) {
      throw new IllegalStateException(
          "ObjectSize should not be passed (see bug 40718) instances of CachedDeserializable: "
              + o);
      // if (((VMCachedDeserializable)o).getDeserializedCopy() instanceof TestObjectSizerImpl) {
      // TestObjectSizerImpl obj = (TestObjectSizerImpl)((VMCachedDeserializable)o)
      // .getDeserializedCopy();
      // return Sizeof.sizeof(obj.one) + Sizeof.sizeof(obj.two)
      // + Sizeof.sizeof(obj.three);
      // }
      // else if (((VMCachedDeserializable)o).getDeserializedCopy() instanceof TestNonSizerObject) {

      // TestNonSizerObject testNonObjectSizerObject =
      // (TestNonSizerObject)((VMCachedDeserializable)o)
      // .getDeserializedCopy();
      // return testNonObjectSizerObject.getTestString().length();
    } else {
      return ObjectSizer.DEFAULT.sizeof(o);
    }

  }
Test object which implements ObjectSizer, used as Key/Value in put operation as well as used as a
Sizer for HeapLru testing.
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/TestObjectSizerImpl.java