ISIS-2782, which is closely related. And discussion at https://the-asf.slack.com/archives/CFC42LWBV/p1625205578149000?thread_ts=1624911448.097500&cid=CFC42LWBV
Rationale here is: encapsulation, "tell not ask".
- Our definition of a property or collection should be either with a publicly available getter or setter, or a field annotated with @Property or @Collection.
- Our definition of an action should be either a publicly available method (if explicit actions config property not set), or a method with any visibility and annotated with @Action.
- Our definition of a supporting method is either one with public visibility or with some other visibility but annotated with @MemberSupport.
See this blog https://thorben-janssen.com/access-strategies-in-jpa-and-hibernate/ for reasons as to why field-level annotations are also recommended for ORMs (JPA in this case).