Reflection into Builders and ArrayList

In order to get my builders into a factory (like that):

public Class<? extends ILink> getLinkImplClass(){
    return LinkJPA.class;
}

public LinkBuilder getLinkBuilder() throws BuilderException {
    return new LinkBuilder(getLinkImplClass());
}

I use a delegateBuilder :

public class DelegateBuilder<T> {
private final Constructor<T> constructor;

public DelegateBuilder(Class<? extends T> constructorClass, Class<?>[] expectedTypes) throws BuilderException {
    try {
        constructor = (Constructor<T>) constructorClass.getConstructor(expectedTypes);
    } catch (NoSuchMethodException e) {
        throw new BuilderException(e);
    }
}

public T build(Object[] params) throws BuilderException {
    try {
        return constructor.newInstance(params);
    } catch (Exception e) {
        throw new BuilderException(e);
    }
}

}

It works fine for several builder, but when I've to use a Generic List it doesn't.

This is my InventoryBuilder :

public class InventoryBuilder {
    private DelegateBuilder<IInventory> delegateBuilder;
    /**
     * List of items to set to the inventory to build
     */
    private List<IItem> items;

    /**
     * Public constructor of the InventoryBuilder
     */
    public InventoryBuilder(Class<? extends IInventory> constructorClass) throws BuilderException {
        items = new ArrayList<>();
        delegateBuilder = new DelegateBuilder<>(constructorClass,
                new Class[]{items.getClass()});
    }

    public InventoryBuilder addItems(List<IItem> items)
    {
        this.items.addAll(items);
        return this;
    }

    public InventoryBuilder addItems(IItem ... items)
    {
        this.items.addAll(Arrays.asList(items));
        return this;
    }

    /**
     * Function used to build the new Inventory
     *
     * @return
     *              The new Inventory
     */
    public IInventory build() throws BuilderException {
        return delegateBuilder.build(new Object[]{items});
    }
}

(Sorry I don't find how to put correctly the previous code)

items.getClass() seems to be an ArrayList and not a ArrayList<IITem>.

Is there a solution for this ?