Merge pull request #4237 from awaterme/master

#3328: GML3 - Writing features with multiple geometries

src/ol/format/gml/gml3format.js

@@ -1070,7 +1070,7 @@ ol.format.GML3.prototype.writeFeatureElement =
     if (value !== null) {
       keys.push(key);
       values.push(value);
-      if (key == geometryName) {
+      if (key == geometryName || value instanceof ol.geom.Geometry) {
         if (!(key in context.serializers[featureNS])) {
           context.serializers[featureNS][key] = ol.xml.makeChildAppender(
               this.writeGeometryElement, this);