Misleading `AggregateReference.getId()` `@Nullable` annotation

[chrshnv]

When I work with AggregateReference I get Intellij warning “Argument ‘entity.getMachine().getId()’ might be null ”.
Looking through the AggregateReference code I do find the Nullable annotation on the getId method, but at the same time in the code of the only implementation there is an explicit assert that the passed id cannot be null.

public IdOnlyAggregateReference(ID id) {
            Assert.notNull(id, "Id must not be null");
            this.id = id;
 }

I think the Nullable annotation should be removed from the getId method.

[mp911de]

We've decided to remove the @Nullable annotation as we expect aggregate references to be valid. While the declaration has been on the interface and therefore, other implementations could return a nullable identifier, we consider a nullable identifier a broken reference. null represents for us a transient object. While in SQL, unique Id indices could have a single entry for a null value, we don't want to stretch ourselves to what is permissible at the limits of SQL.

In any case, thanks for bringing this up, that's fixed now.