save
Persists via the delegate, then emits one lifecycle event carrying the saved instance.
The prior status is read only when the incoming status is non-ACTIVE, keeping fresh ACTIVE inserts read-free. A PropositionStatusChanged is emitted when a prior entry existed with a different status; otherwise a PropositionPersisted is emitted. The delegate always completes before the event fires.
Return
The instance returned by delegate.save, also carried in the emitted event.
Parameters
proposition
The proposition to persist.