ninja-core/src/main/java/ninja/cache/NinjaCache.java
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()));
        }
    }
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()));
        }
    }
Utility that check that an object is serializable.