Shopify/active_merchant — pull request #458 by mattwhite (2012-09-18 15:29:41+00:00)
Title: Add option to change the outstanding balance of a PayPal recurring billing profile 

Adds support for OutstandingBalance in the UpdateRecurringPaymentsProfileReq request.

I have also added "n1" prefixes to the Username, Password, Subject, and Signature fields in the add_credentials() functions. This is due to a bug with PayPal that seems to only be triggered when changing the outstanding balance.