/**
* Make this Mapper instance a reference to another Mapper.
*
* You must not set any other attribute if you make it a reference.
* @param Reference $r
* @throws BuildException
*/
public function setRefid(Reference $r)
{
if ($this->type !== null || $this->from !== null || $this->to !== null) {
throw DataType::tooManyAttributes();
}
parent::setRefid($r);
}
