On success, an array 'invoices' of objects is returned. Each object contains 'label', 'rhash', 'complete' (a boolean), and 'expiry_time' (a UNIX timestamp). If the 'msatoshi' argument to lightning-invoice(7) was not "any", there will be an 'msatoshi' field. If the invoice has been paid, there will be a 'pay_index' field.