public function get_shipping_classes() {
		if ( empty( $this->shipping_classes ) ) {
			$classes                = get_terms(
				'product_shipping_class',
				array(
					'hide_empty' => '0',
					'orderby'    => 'name',
				)
			);
			$this->shipping_classes = ! is_wp_error( $classes ) ? $classes : array();
		}
		return apply_filters( 'woocommerce_get_shipping_classes', $this->shipping_classes );
	}