Remove class= attribute

The class Attribute tells Simple which implementation of List you use. If it's missing, Simple will look for a proper class itself.

One solution is to use ArrayList instead of List:

@ElementList
protected ArrayList<Element> elements;

Now Simple wont add the class-Attribute.

Another way:

@Path("elements")
@ElementList(inline=true)
protected List<Element> elements;

This inlines your List (no elements-Tag is used) but puts it into a "new" elements-Tag