RDLC ASP.NET report viewer - default empty datasource

I forgot and can't find code samples about how to set empty datasource for the report viewer

<rsweb:ReportViewer runat="server" ProcessingMode="Local" ...><LocalReport ReportPath="xxx.rdlc"><DataSources>
                    ???</DataSources></LocalReport></rsweb:ReportViewer>

something need to fill in the ??? section

so when the page is initially loaded, it won't show any error, just a viewer with blank report

y