I've found out more information:

I'm working on updating/implementing @jgehrett's first pass at this API in homerun.

It turns out that the ShippingAddress class considers telephone to be a required field currently.  I am temporarily putting a value of "unknown" into this field to allow a ShippingAddress to be created.

Do we want to:
1. Keep the telephone "unknown"
2. Require a telephone
3. Change the validation to not require a telephone

Thanks.