The API Reference documentation for the /v1/charges endpoint shows that it can take an "expand" parameter as an array of strings to "specify fields in the response for expansion". However the documentation doesn't list what fields can be expanded, and anything I try doesn't seem to work.
Ideally I'd like to expand the customer data. I've tried sending this as an array query like 'expand=customer', as well as a string like 'expand=customer', and neither work. I've also tried this with 'customers', 'order', 'orders', etc, trying to stumble upon anything that actually does work, to no avail.
Changing the expand parameters in the API Reference form and then submitting a request through the online form doesn't appear to change the request at all. So I think that's an issue with the API reference, but I've also attempted this with my own code and it doesn't work either.
Any advice here would be appreciated.