olemus
väike lihtne objekt, mille samasus ei põhine identiteedil
= a small simple object whose equality isn't based on identity

ülevaateid
https://enterprisecraftsmanship.com/posts/entity-vs-value-object-the-ultimate-list-of-differences/
https://en.wikipedia.org/wiki/Value_object
https://martinfowler.com/bliki/ValueObject.html
https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=b381696859ca70256243b23c19ef148f51911ee3