Custom SelectionFactory with generic EditorDescriptor

CustomSelectionFactory.cs

using System;
using System.Collections.Generic;
using System.Linq;
using EPiServer.Shell.ObjectEditing;

namespace Alloy.Business.Properties.CustomSelectionFactory
{
    class CustomSelectionFactory<T> : ISelectionFactory
    {
        public IEnumerable<ISelectItem> GetSelections(ExtendedMetadata metadata)
        {
            var settings = Activator.CreateInstance<T>() as Dictionary<string, string>;

            if (settings == null)
            {
                yield break;
            }

            foreach (var setting in settings.ToList())
            {
                yield return new SelectItem()
                {
                    Value = setting.Key.ToLower(),
                    Text = setting.Value
                };
            }
        }
    }
}

EditorDescriptor.cs

using System;
using System.Collections.Generic;
using EPiServer.Shell.ObjectEditing;
using EPiServer.Shell.ObjectEditing.EditorDescriptors;

namespace Alloy.Business.Properties.CustomSelectionFactory
{
    public class CustomSelectionFactoryEditorDescriptor<TSelectionFactory> : EditorDescriptor
    {
        public override void ModifyMetadata(ExtendedMetadata metadata, IEnumerable<Attribute> attributes)
        {
            SelectionFactoryType = typeof(CustomSelectionFactory<TSelectionFactory>);
            ClientEditingClass = "epi-cms/contentediting/editors/SelectionEditor";
            base.ModifyMetadata(metadata, attributes);
        }
    }
}

SelectionSettings.cs

namespace Alloy.Settings
{
    public class SelectionSettings : Dictionary<string, string>
    {
        public SelectionSettings()
        {
            Add("key", "value");
            Add("key1", "value");
            Add("key2", "value");
            Add("key3", "value");
        }
    }
}