Returning classes with lists

[Barry Hathaway]

I have a method that returns a class containing a couple of lists; 
however, when it executes I get:

javax.xml.bind.JAXBException: class java.util.ArrayList nor any of its 
super class is known to this context.

The method is:

    @WebMethod(operationName="query", action="urn:query")
    public QueryResultSet query(@WebParam(name="sparcql")String sparcql)

where QueryResultSet is:

    public class QueryResultSet {
        private List<Object> columnNames;
        private List<Object> resultSet; <- Object will actually be a 
List<Object>
        ... getters and setters
    }

How do you go about annotating the classes so the it gets marshalled 
correctly?
Thanks.

Barry Hathaway