shadow generator serialization issue

serialization uses mesh id to add mesh to the shadowgenerator renderlist
if two or more mesh have same id then during deserialization only one mesh gets added to the renderlist
and thus only one of them displays shadow

Instead of meshid maybe we should use  the mesh's uniqueId ?

Today, as a workaround, just before I serialize a scene,  I rename all mesh id and give each of them unique id