@Override
  public SerializedCacheValue<?> getSerializedOldValue() {
    @Unretained(ENTRY_EVENT_OLD_VALUE)
    final Object tmp = basicGetOldValue();
    if (tmp instanceof CachedDeserializable) {
      CachedDeserializable cd = (CachedDeserializable) tmp;
      if (!cd.isSerialized()) {
        return null;
      }
      return new SerializedCacheValueImpl(this, getRegion(), re, cd, oldValueBytes);
    } else {
      return null;
    }
  }
@return null if old value is not serialized; otherwise returns a SerializedCacheValueImpl
        containing the old value.
geode-core/src/main/java/org/apache/geode/internal/cache/EntryEventImpl.java