Namespace for XMLList on JMSSerializerBundle

I'm trying to create a XML using JMSSerializerBundle, and this XML must have some nodes with namespace (please see gist linked below for full code example) but I get a node with wrong namespace, and this wrong namespace is repeated even in parent node (XMLList).

Have you ever faced a problem like this? Can you please help me figuring out how to solve this issue?

Thanks a lot.