in src/main/scala/com/gu/invoicing/invoice/Impl.scala [129:138]
def joinInvoicesWithPayment(
invoices: List[Invoice],
payments: List[Payment],
paymentMethods: List[PaymentMethod],
): List[InvoiceWithPayment] = {
invoices.flatMap { invoice => // filter out invoices with no associated payment methods
getPaymentMethod(invoice.id, invoices, payments, paymentMethods)
.map { InvoiceWithPayment(invoice, _) }
}
}