Optional Shipping address

[nstapelbroek]

Hi there, loving the library so far. Thank you!

Describe the bug I'm selling digital products, so there is no need for a shipping address. As far as I can tell the API reference for creating an order also tells me that the shipping address is optional.

The library however, requires a shipping address because the default zero value of a mollie.Order.ShippingAddress is invalid when creating an order.

To Reproduce

1. Install library in your project
2. Create an order without setting the shipping address
3. Acknowledge mollie returns an error telling you that the shipping address is invalid.

Expected behavior I should be able to create an order without shipping address.

Additional context I could work on a PR that makes the shipping address optional. Not requesting you to do the work, just merely wondering if I'm missing something 😄

[VictorAvelar]

This is an interesting one, I was under the impression that if the field is empty then when encoding json you would not get it.

I will try to reproduce it but if you have an idea on how to solve it, please go ahead.

[VictorAvelar]

Updated and included in changes to be tagger with v4