SO Generic class with dependent generic types, cannot specia

// For http://stackoverflow.com/questions/13931900/generic-class-wi

public class Test {
    // This works
    public static <X> void test(LabelField<X> lf) {
        LabelProvider<X> lp = lf.getLabelProvider();
        new Wrapper<X, LabelField<X>>(lf, lp);
    }
}

class Wrapper<V, F extends Field<V>> {

    private F field;
    private LabelProvider<V> labelProvider; // Converts from V to String

    // Since we have no guarantee that F has a LabelProvider, one is explicitely supplied.
    public Wrapper(F field, LabelProvider<V> labelProvider) {
        this.field = field;
        this.labelProvider = labelProvider;
    }

    public Wrapper(LabelField<V> labelField) {
        // This doesn't work, why ?
        this(labelField, labelField.getLabelProvider());
    }

    public String getLabel() {
        return labelProvider.getLabel(field.getValue());
    }

    public F getField() {
        return field;
    }

    public V fetValue() {
        return field.getValue();
    }
}

interface Field<V> {
    V getValue();
}

interface LabelProvider<V> {
    String getLabel(V v);
}

interface LabelField<V> extends Field<V> {
    LabelProvider<V> getLabelProvider();
}