code: void checkSerializable(Object value) {
          if (value != null && !(value instanceof Serializable)) {
              throw new CacheException(
                      "Cannot cache a non-serializable value of type "
                              + value.getClass().getName(),
                      new NotSerializableException(value.getClass().getName()));
          }
      }
docs: Utility that check that an object is serializable.