org.immutables:ordinal (maven):  API and support runtime classes for implementing immutable objects as set enum-like object values, accumulated in so called "domains". This allows for special performance optiomization, like using bit-sets to efficiently calculate inclusion in set or set differences. 
Keywords: annotation-processor|builder|gson|guava|immutable-collections|immutable-datastructures|immutable-objects|immutables|jackson|java