Using sets in JDO

I have a model which contains a java.util.Set object as a 开发者_开发百科member. How do I persist this using JDO? Specifically, how do I define the XML in the .jdo file?

class MyClass {
    Set<String> data;

    private MyClass() {
    }
}

Perhaps looking in the docs for your JDO implementation for 1-N relations with non-PC objects