xxxproject/Demo/Data/Repository/GroupRepositoryImpl.cs

using Demo.Data.LocalData;
using Demo.domain.Models;
using System.Collections.Generic;

namespace Demo.Data.Repository
{
    public class GroupRepositoryImpl
    {
        public List<GroupLocalEntity> GetAllGroups;
        public GroupRepositoryImpl() {
            GetAllGroups = LocalStaticData.groups;
        }

        public void AddGroup(GroupLocalEntity newGroup)
        {
            GetAllGroups.Add(newGroup);
        }
    }
}