public class ExceptionConverter : IExceptionConverter
{
    //need the parameter
    public HttpStatusCode Convert(/*need to pass this the repository method*/)
    {
        try
        {
            //call the void repository method here
        }
        catch (Exception exception)
        {
            if (exception is ObjectNotFoundException)
                return HttpStatusCode.NotFound;
            if (exception is InvalidOperationException)
                return HttpStatusCode.BadRequest;
        }
        return HttpStatusCode.OK;
    }
}

public interface IHandleCrudOperations
{
    //All of these methods need to be able to take in many different parameters
    //They will always need a parameter though
    void Remove();
    void Add();
    void Edit();
    void Clone();
}

//userRepository
public void Remove(int userKey)
public void Add(User user)
public void Edit(User user)
public void Clone(CloneUserRequest)

//groupRepository
public void Remove(string groupName)
public void Add(string groupName)
public void Edit(EditGroupRequest)
public void Clone(CloneGroupRequest)

public interface IHandleCrudOperations
{
    //All of these methods need to be able to take in many different parameters
    //They will always need a parameter though
    void Remove<T>(T item);
    void Add<T>(T item);
    void Edit<T>(T item);
    void Clone<T>(T item);
}

//userRepository
public void Remove<T>(T item)
{
    //SERIOUS code smell here
    var userKey = (int)(object)item
    //stuff
}

//groupRepository
public void Remove<T>(T item)
{
    //SERIOUS code smell here
    var groupName = (string)(object)item
    //stuff
}

public interface IHandleCrudOperations<TRemove, TAdd, TEdit, TClone>
{
    void Remove(TKey item);
    void Add(TAdd item);
    void Edit(TEdit item);
    void Clone(TClone item);
}