public function set_discount_type( $discount_type ) {
		if ( 'percent_product' === $discount_type ) {
			$discount_type = 'percent'; // Backwards compatibility.
		}
		if ( ! in_array( $discount_type, array_keys( wc_get_coupon_types() ), true ) ) {
			$this->error( 'coupon_invalid_discount_type', __( 'Invalid discount type', 'woocommerce' ) );
		}
		$this->set_prop( 'discount_type', $discount_type );
	}