how to get a property type from an content object in a map

The next code is an adaptation of my code and I hope it can help you.

Order.java

public class Order {
    ...
    private Map<Integer, Item> items = new LinkedHashMap<Integer, Item>();
    ...
}

Item.java

public abstract class Item {

    public abstract Object getValue();
    public abstract void setValue(Object value);

}

ItemInt.java

public class ItemInt extends Item {

    private Integer number;

    @Override
    public Integer getValue() {
        return number; 
    }

    @Override
    public void setValue(Object value) {
        number = (Integer) value;
    }
}

ItemFloat.java

public class ItemFloat extends Item {

    private Float number;

    @Override
    public Float getValue() {
        return number; 
    }

    @Override
    public void setValue(Object value) {
        number = (Float) value;
    }
}

I'm trying to get the property type with the next string "items[2].value"and it doesn't work. How can I make it? The results would be int or float.

Order order = ...;
....
final Class<?> clazz = new PropertyUtilsBean().getPropertyType(order, "items[2].value");