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();