4.5.0 can introduce new features and deprecations to be removed in 5.x. 4.5.0 will receive feature backports from 5.x where the core team or community think they will help future upgrade paths or don't rely on breaking changes. Community contributions are always welcome.

• ChronosDate compatibility. Deprecations for Date, and Mutable classes need to be added to chronos 2.x. 4.5 needs a way to opt into the new abstractions. Methods on the type classes seem ideal. We did this for the mutable -> frozen object changes and that worked out really well.
• EntityTrait::has() no longer returns false on null values. We need a path to enable this mode by default on 4.5. Could be a global config setting, or something that is enabled at the Table level.