Annotation idea: WritesGuardedBy

### Description of the problem / feature request:

`WritesGuardedBy` annotation for fields that should be only written when a lock is held, but there can be reads outside of critical section. Example use: double-checked locking pattern.

### Feature requests: what underlying problem are you trying to solve with this feature?

Provide a way to concisely express "this variable is updated/stored (lazily) within double-checked locking" in code. Add a tool to improve the safety of such patterns (nobody will be able to accidentally write to the field outside a critical section).

### Have you found anything relevant by searching the web?

No