my-trello-backend/MyTrelloWeb/VCommon/Collections/CollectionExtensionMethod.cs

using System.Collections.Generic;

namespace MyTrelloWeb.VCommon.Collections
{
    public static class CollectionExtensionMethod
    {
        public static bool IsNullOrEmpty<T>(this ICollection<T> source) => source == null || source.Count <= 0;
    }
}