为什么Fluent的NHibernate中的AutoMapping会忽略枚举类型？

我有以下枚举类型:

public enum EnumType
{
    E1,
    E2
}

用于以下类:

public class X
{
    public virtual int? Id { get; set; }

    public virtual EnumType EnumProperty { get; set; }

    public virtual string S { get; set; }
}

我想使用NHibernate在数据库中保留此类实例.为避免编写样板代码,我试图使用自动映射功能,如下所示:

private ISessionFactory CreateSessionFactory()
{
    var mappings = AutoMap
        .AssemblyOf(new MyAutoMappingConfiguration());

    this.NHibernateConfiguration = Fluently
        .Configure()
        .Database(FluentNHibernate.Cfg.Db.MsSqlConfiguration.MsSql2012.ConnectionString(
                b => b.FromConnectionStringWithKey("x")))
        .Mappings(m => m.AutoMappings.Add(mappings))
        .BuildConfiguration();

    return this.NHibernateConfiguration.BuildSessionFactory();
}

这里MyAutoMappingConfiguration看起来是这样的:

public class MyAutoMappingConfiguration: FluentNHibernate.Automapping.DefaultAutomappingConfiguration
{
    public override bool ShouldMap(Type type)
    {
        return type.Namespace == "Domain";
    }

    public override bool IsComponent(Type type)
    {
        return type.Name == "EnumType";
    }
}

当我使用从此配置生成的模式来创建数据库时:

new SchemaExport(this.sessionProvider.NHibernateConfiguration)
    .Execute(true, true, false);

正在生成并执行以下脚本:

if exists (select * from dbo.sysobjects where id = object_id(N'[X]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [X]

create table [X] (
    Id INT not null,
   S NVARCHAR(255) null,
   primary key (Id)
)

var mappings = AutoMap
    .AssemblyOf(new MyAutoMappingConfiguration())
    .Override(m =>
    {
        m.Table("X");
        m.Id(x => x.Id);
        m.Map(x => x.EnumProperty);     // this works
        m.Map(x => x.S);
    });

if exists (select * from dbo.sysobjects where id = object_id(N'[X]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [X]

create table [X] (
    Id INT not null,
   EnumProperty NVARCHAR(255) null,
   S NVARCHAR(255) null,
   primary key (Id)
)

public override bool ShouldMap(Member member)
{
    var result = base.ShouldMap(member);
    return result;
}