Snapping does not work for WFSLayer in ArcGIS JavaScript API 3

I have a web application that I now need to use WFSLayer for some of the map layers. The problem is that snapping does not seem to work for WFS layers.

The layer I use for drawing is a FeatureLayer. I need to be able to snap to features in other layers.

I have this code:

var snappingOptions = {
    tolerance: 20,
    alwaysSnap: true
};

snappingOptions.layerInfos = [];
var layerIds = map.graphicsLayerIds;
layerIds.forEach(function (layerId) {
    var lyr = map.getLayer(layerId);
    if (lyr instanceof FeatureLayer || lyr instanceof WFSLayer) {
        var isLyrSnappable = true;
        if (snappableLayerUrls) {
            isLyrSnappable = snappableLayerUrls.some(function (layerUrl) {
                if (layerId.toLowerCase() === layerUrl.toLowerCase() || (lyr.url && lyr.url.toLowerCase() === layerUrl.toLowerCase())) {
                    return true;
                }
                return false;
            });
        }
        var layerInfo = { layer: lyr };
        if (isLyrSnappable) {
            if (lyr.geometryType === "esriGeometryPolygon") {
                layerInfo.snapToEdge = false;
                layerInfo.snapToVertex = true;
            } else if (lyr.geometryType === "esriGeometryPolyline") {
                layerInfo.snapToVertex = true;
            } else if (lyr.geometryType === "esriGeometryPoint") {
                layerInfo.snapToPoint = true;
            }
            snappingOptions.layerInfos.push(layerInfo);
        }

    }
});
console.log('snappingOptions', snappingOptions);
map.enableSnapping(snappingOptions);

When I look at the snapping options at the end, I se that my WFS layers are present in the snappingOptions.layerInfos array.

When I activate a draw tool, the other FeatureLayer layers are snapped to, but not the WFSLayer layers.

Is not snapping supported for the WFSLayer?

How can I get around this?