This event occurs when an invoice is updated.

Note that this event will NOT occur when an invoice is marked paid (because the actual invoice hasn't changed in that case -- a payment has just been applied to the existing, unchanged invoice). If you want to know when an invoice changes status (e.g. from "unpaid" to "paid") you should listen for the status webhook on invoices.

Note these fields:

• context_str = invoice
• context_id = ... (this will be the invoice_id of the invoice)
• event = update