Java bind Consumer through reflection

I do need to use reflections and it mostly works fine. I now just have a prolem, as I don't know how I could do this. This is what it would look lik.

Private Consumer<String> messageUpdate;

public void setMessageUpdate(Consumer<String> messageUpdate)
{
    this.messageUpdate = messageUpdate;    
}

public void test(String className)
{
    Class cls = Class.forName("package." + className);
    // Ofcourse the constructor is not empty normally
    Constructor<Class> constructorStr = cls.getConstructor();
    Object obj = constructorStr.newInstance();

    Class[] params = new Class[1];
    params[0] = Consumer.class;  // Here I don't know what I need

    Method method = cls.getDeclaredMethod("setMessageUpdate", params);
    method.invoke(obj, messageUpdate); // Here I don't know what I need
}

Without reflection I would do this:

testClass tc = new testClass();
tc.setMessageUpdate(messageUpdate::accept);
// or

tc.setMessageUpdate(new Consumer<String>() {
    @Override
    public void accept(String s) {
        messageUpdate.accept(s);
    }
});

Does anybody know the answer?