Locking (RAP managed locks)
What it is
RAP's declarative locking: you mark a `lock master` (and dependent locks down the composition) in the BDEF, and the framework acquires the right locks during a change — replacing hand-written ENQUEUE/DEQUEUE for the BO.
Why it matters for Clean Core
It keeps concurrency control inside the business object and consistent across consumers, rather than scattered ENQUEUE calls. Combined with ETag, it's how RAP keeps transactional integrity in a stateless OData world.
Common pitfall
Hand-rolling enqueue logic alongside a managed BO, or forgetting to declare dependent locks on children. Let the BDEF own locking; declare the lock master once and let it cascade.