public interface AfterClearFlusher
After BeanMapper calls the clear() method on a collection, it will check for the
presence of AfterClearFlusher instance. All instances found will be executed. The
use case triggering this functionality is the fact that Hibernate's @OneToMany first
executes insert SQL-statements, before the delete SQL statements. With constraints,
this is an issue. By forcing the flush after a clear, Hibernate is forced to first
execute its delete SQL-statements, before the inserts.