server/src/Infrastructure.EntityFramework/Models/Group.cs

using System.Collections.Generic;
using AutoMapper;

namespace Bit.Infrastructure.EntityFramework.Models
{
    public class Group : Core.Entities.Group
    {
        public virtual Organization Organization { get; set; }
        public virtual ICollection<GroupUser> GroupUsers { get; set; }
    }

    public class GroupMapperProfile : Profile
    {
        public GroupMapperProfile()
        {
            CreateMap<Core.Entities.Group, Group>().ReverseMap();
        }
    }
}