Unity - Adding events in C#

Events.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.EventSystems;
using UnityEngine.UI;

public class Events : MonoBehaviour/*, IPointerUpHandler, IPointerEnterHandler, IPointerClickHandler*/
{
    void Start()
    {
        EventTrigger myEventTrigger = GetComponent<EventTrigger>(); //you need to have an EventTrigger component attached this gameObject
        Debug.Log(myEventTrigger);
        myEventTrigger.AddListener(EventTriggerType.PointerClick, onClickListener);
        myEventTrigger.AddListener(EventTriggerType.PointerUp, OnPointerUp);
    }

    public void onClickListener(PointerEventData eventData)
    {
        Debug.Log("ExtensionMethod");
    }

    public void EnClickListener()
    {
        Debug.Log("ExtensionMethod 2");
    }

    public void OnPointerClick(PointerEventData eventData)
    {
        Debug.Log("OnPointerClick");
    }

    public void OnPointerEnter(PointerEventData eventData)
    {
        Debug.Log("OnPointerEnter on puzzle piece");
    }

    public void OnPointerUp(PointerEventData eventData)
    {
        Debug.Log("tapped on puzzle piece");
    }

    void Update()
    {
        
    }
}

ExtensionMethods.cs

using UnityEngine.EventSystems;
using UnityEngine;

public static class ExtensionMethods
{
    public static void AddListener(this EventTrigger trigger, EventTriggerType eventType, System.Action<PointerEventData> listener)
    {
        EventTrigger.Entry entry = new EventTrigger.Entry();
        entry.eventID = eventType;
        entry.callback.AddListener(data => listener.Invoke((PointerEventData)data));
        trigger.triggers.Add(entry);
    }
}