/**
  * 
  * @param \ifirma\InvoiceMap $invoiceMap
  * @return \ifirma\GetPdfInterface
  */
 private function _getInvoiceResponseObject(InvoiceMap $invoiceMap)
 {
     switch ($invoiceMap->{InvoiceMap::COLUMN_NAME_INVOICE_TYPE}) {
         case InvoiceMap::INVOICE_TYPE_BILL:
             return InvoiceBill::get($invoiceMap->{InvoiceMap::COLUMN_NAME_INVOICE_ID});
             break;
         case InvoiceMap::INVOICE_TYPE_NORMAL:
             return Invoice::get($invoiceMap->{InvoiceMap::COLUMN_NAME_INVOICE_ID});
             break;
         case InvoiceMap::INVOICE_TYPE_PROFORMA:
             return InvoiceProforma::get($invoiceMap->{InvoiceMap::COLUMN_NAME_INVOICE_ID});
             break;
         case InvoiceMap::INVOICE_TYPE_SEND:
             return InvoiceSend::get($invoiceMap->{InvoiceMap::COLUMN_NAME_INVOICE_ID});
             break;
     }
 }