Session session = ...;
Company company = session.byNaturalId( Company.class )
.using( "taxIdentifier","abc-123-xyz" )
.load();
PostalCarrier carrier = session.byNaturalId( PostalCarrier.class )
.using( "postalCode",new PostalCode(... ) )
.load();
Department department = ...;
Course course = session.byNaturalId( Course.class )
.using( "department",department )
.using( "code","101" )
.load();