How set subreport url with Spring 4 and Jasper reports

I'm creating a Spring Boot, Spring MVC, Hibernate, Jasper report 6 application.

I want to render a PDF exposing it via REST.

This is the controller:

@PreAuthorize("isAuthenticated()")
    @RequestMapping(value = "/ticketBundles/{id}/export", method = RequestMethod.GET)
    public ModelAndView exportVoucherB2B(@PathVariable("id") Long id, Locale locale) throws Exception {
        TicketBundle ticketBundle = ticketBundleRepository.findOne(id);
        if (ticketBundle != null) {
            ModelMap model = new ModelMap();
            model.addAttribute("datasource", new JREmptyDataSource(1));         
            model.addAttribute("model", ticketBundle);
            //subreports rows
            model.addAttribute("rows", new JRBeanCollectionDataSource(ticketBundle.getRows()));
            model.addAttribute("footer", footer);
            model.addAttribute("taxNote", taxNote);
            return new ModelAndView("TicketBundlePdfView-IT", model);
        } else {
            // TODO
            throw new RestNotFoundException("");
        }
    }

And this is my views.properties to render correctly my ModelAndView:

TicketBundlePdfView-IT.(class)=org.springframework.web.servlet.view.jasperreports.JasperReportsPdfView
TicketBundlePdfView-IT.url=classpath:/reports/tickets/TicketBundle-IT.jrxml
TicketBundlePdfView-IT.reportDataKey=datasource
TicketBundlePdfView-IT.subReportDataKeys=rows
TicketBundlePdfView-IT.subReportUrls=TicketBundleRow-IT.jrxml

According to Spring documentation, this is the right way to do things. Everything work except I'm not able to define the key of subReportUrls. Checking JasperReportsPdfView I see that subReportUrls is a Properties

/**
     * Stores the paths to any sub-report files used by this top-level report,
     * along with the keys they are mapped to in the top-level report file.
     */
    private Properties subReportUrls;

I am wondering how I can set the key name of that property. On Spring documentation they are speaking about an xml file like this:

<property name="subReportUrls">
    <map>
        <entry key="ProductsSubReport" value="/WEB-INF/reports/subReportChild.jrxml"/>
    </map>
</property>

They didn't mention how to do this with a plain properties file like mine. Is that possibile?