One of the stated goals for R4B is to be as backwards-compatible as possible.
While testing R4 -> R4B migration paths, I noticed that there was an unexpected breakage on the DeviceDefinition resource type.

The cause of the breakage is backwards-incompatible updates to the ProductShelfLife re-usable type.

Through discussion with Lloyd and Rik, we thought of a few different options for avoiding the breakage.

The option I favor is to update DeviceDefinition in R4B to use an in-line BackboneElement that matches the R4 structure for this shelfLifeStorage element.
That way, PackagedProductDefinition can continue to use the updated

Then, R5 (https://build.fhir.org/productshelflife.html) can stay just the way it is and PackagedProductDefinition in R4B (which has no backwards-compatibility issues) will be as close to the R5 version as possible.

Originally raised and discussed on Zulip at https://chat.fhir.org/#narrow/stream/179166-implementers/topic/R4B.20compatibilty/near/269337460