public ClassDoc exception() {
        ClassDocImpl exceptionClass;
        if (!(holder instanceof ExecutableMemberDoc)) {
            exceptionClass = null;
        } else {
            ExecutableMemberDocImpl emd = (ExecutableMemberDocImpl)holder;
            ClassDocImpl con = (ClassDocImpl)emd.containingClass();
            exceptionClass = (ClassDocImpl)con.findClass(exceptionName);
        }
        return exceptionClass;
    }