Generics return type not working

Question

I'm going through example.

public interface Visitor<T> {
    public void visit(T e);
}

class Sum<T extends Integer> implements Visitor<T> {

    private int sum = 0;



    @Override
        public void visit(T element) {
            sum += element;
        }

        public T value() {
            return sum;
        }

}

The return statement T value() return sum is giving error stating that Type mismatch: cannot convert from int to T. Why it is so and how to fix the problem.