Recurly_Invoice::getPdf does not take invoice_number_prefix into account

[jaanttil]

Recurly_Invoice::getPdf does not work for invoices where invoice_number_prefix exist. The workaround is to use getInvoicePdf with the following argument: $invoice->invoice_number_prefix . $invoice->invoice_number

[drewish]

Ah yeah seems like we over looked that. I think we can just change it to:

public function getPdf($locale = null) {
  return Recurly_Invoice::getInvoicePdf($this->invoiceNumberWithPrefix(), $locale, $this->_client);
}

And have change the docs for Recurly_Invoice::getInvoicePdf to specify that the prefix be included with the invoice number.