code: public ArrayList<String> cart_cartId_coupon_POST(String cartId, String coupon) throws IOException {
  		String qPath = "/order/cart/{cartId}/coupon";
  		StringBuilder sb = path(qPath, cartId);
  		HashMap<String, Object>o = new HashMap<String, Object>();
  		addBody(o, "coupon", coupon);
  		String resp = execN(qPath, "POST", sb.toString(), o);
  		return convertTo(resp, t1);
  	}
docs: Add a new coupon to cart
  
  REST: POST /order/cart/{cartId}/coupon
  @param cartId [required] Cart identifier
  @param coupon [required] Coupon identifier