post https://sandboxpurchasesapi.connexpay.com/api/v1/merchantsupplier/settings
This endpoint allows you to create and tokenize a suppliers bank account information without actually making the Issue ACH call. That tokenized bank account can then be used in future Issue ACH or Issue ACH Lite API requests so you don't have to store the actual bank account information.
The bankAccountGuid is the tokenized bank account identifier. This is what should be passed in future Issue ACH or Issue ACH Lite requests.