How Do I Change Values on an Existing Business Entity Instance?
There are really three steps:
• Ask the existing entity for its DTO.
• Change the appropriate values on the DTO.
• Call setDTO() on the entity instance.

Person_DTO dto = person.getDTO();
dto.setAddress1("invalid value");
person.setDTO(dto);
Necessary Change Handlers will fire to validate the change to this "person" object as well as other cascading events as specified in the entity's change handlers.