No wsdl elements generated for Exception.class

There is no wsdl element generated for Exception class:

@WebService(name = "CalculatorService", targetNamespace = "http://cxf.apache.org/calculator")
public class Caculator {
@WebMethod(operationName = "addNumber")
public Integer addNumber(@WebParam(name = "itemA") Integer itemA, @WebParam(name = "ItemB") Integer itemB)
throws java.lang.Exception

{ return itemA + itemB; }

}

The schema element, wsdl part , fault and soap fault elements are expected.