public function get_changes() {
		$changed_props = parent::get_changes();
		$subs          = array( 'shipping', 'billing' );
		foreach ( $subs as $sub ) {
			if ( ! empty( $changed_props[ $sub ] ) ) {
				foreach ( $changed_props[ $sub ] as $sub_prop => $value ) {
					$changed_props[ $sub . '_' . $sub_prop ] = $value;
				}
			}
		}
		if ( isset( $changed_props['customer_note'] ) ) {
			$changed_props['post_excerpt'] = $changed_props['customer_note'];
		}
		return $changed_props;
	}