As such with O/R this would get mapped with a join to two tables because of the 1:n relation. For enum reasons one could also consider to use a third join-table, so enum-entries aren't repeated inside the enum table all the time.
Never the less I would like to avoid joins (enums are stupid types and I don't consider them as entities but rather as table-column).
I thought about writing a custom converter, so the enum is serialized into a comma separated string, but I think such an encoding as kind of bad practice. Is there maybe a JPA + hibernate homegrown solution for mapping the 1:n(asEnum) relation?
I always wrap my enums in persistable enum entities and map those, providing an easy way to get the actual enum out of the enum entity wrapper. For example:
The above gives you a simple 2 table bidirectional one-to-many / many-to-one relationship between an enum and an entity which needs a collection of those enums. All you have to do is fill out the usual rest of the bean stuff as well as a way to manage the wrapper correctly (i.e. to get and set the enum itself inside it).