public function load_custom_fields_from_xml_object($xml_object)
 {
     $this->original_custom_fields = array();
     $this->custom_fields = array();
     if (count($xml_object->{'subject_data'}) > 0) {
         foreach ($xml_object->{'subject_data'} as $field) {
             $custom_field = new HighriseCustomField($this->highrise);
             $custom_field->set_id($xml_object->{'id'});
             $custom_field->set_value($xml_object->{'value'});
             $custom_field->set_subject_field_id($xml_object->{'subject_field_id'});
             $custom_field->set_subject_field_label($xml_object->{'subject_field_label'});
             $this->original_custom_fields[$custom_field->get_subject_field_label()] = 1;
             $this->add_custom_field($custom_field);
         }
     }
 }