Other billing system plugin methods

There are other methods on the billing plugin interface:

• addPaymentInstrumentTo – Adds a payment instrument to an account and returns a billing system instrument. For example, an insured’s credit card number or a token that represents it in an external payment system.
• getExistingPaymentInstruments – Returns an array of billing system instruments.
• getInvoiceStreams – Retrieves all invoice streams for a given account.
• getSubAccounts – Retrieves all subaccounts of the account with the given account number. If the account does not exist, returns an empty array. The search for subaccounts is recursive and returns subaccounts of subaccounts also.
• searchForAccounts – Search for accounts in the billing system by using search criteria.