Flutter Razorpay integration

I am developing a flutter app and want to use Razorpay as my payment gateway. I have integrated as per the code provided on pub.dev library. However the UPI payments using third party apps (G pay, PhonePe, et) are failing with a error "bar request error". I need you to check what am I doing wrong and help me rectify it.
Please bid only if you have worked with flutter-razorpay project before.