def before_write_xml
      #TODO# This will go away once containers are fully implemented.
      child_nodes = obtain_class_variable(:@@ooxml_child_nodes)
      child_nodes.each_pair { |child_node_name, child_node_params|
        self.count = self.send(child_node_params[:accessor]).size if child_node_params[:is_array] == :with_count
      }
      true
    end
def before_write_xml
      #TODO# This will go away once containers are fully implemented.
      child_nodes = obtain_class_variable(:@@ooxml_child_nodes)
      child_nodes.each_pair { |child_node_name, child_node_params|
        self.count = self.send(child_node_params[:accessor]).size if child_node_params[:is_array] == :with_count
      }
      true
    end
Subclass provided filter to perform last-minute operations (cleanup, count, etc.) immediately prior to write,
 along with option to terminate the actual write if +false+ is returned (for example, to avoid writing
 the collection's root node if the collection is empty).