Bug? Still persisted when event is cancelled. "Default branch"

We have a plugin for Bitbucket Data Center written with Java SDK.

Ideally the “default branch” property would be part of the event RepositoryModificationRequestedEvent or the Repository class itself. Since we want to set specific restrictions for what a user are allowed to change. Can this be achived in another way?

But, even if I cancel the event RepositoryModificationRequestedEvent, the change for default branch is persisted. To me, this sounds like a bug in the Java SDK/Bitbucket?