Envers does not presently have support for @MapKeyEnumerated which is why you ran into this problem.

There is a workaround assuming you can afford a small model change in order to accomplish the same thing but using @MapKey until we offer support for the other annotation. The workaround is to add a property in your OperationDetails class that is your enum type and then rather than using @MapKeyEnumerated you use @MapKey(name = "yourEnumProperty").