<Layers baseMapType="blank">
  <referenceLayer layerType="EpiDashboard.Mapping.MapServerLayerProperties">
    <referenceLayer>
      <serverName>https://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer</serverName>
      <visibleLayers />
    </referenceLayer>
  </referenceLayer>
</Layers>