Fluent-NHibernate对象化/关联关系映射

好的,我很熟悉Fluent和NHiBiNATE,我不知道如何映射我数据库中存在的这种特定关系。我有下面的ER图,概述了我的表结构。

下面是我当前的C#实体类和Fluent映射:

public class GroupHeader
{
    public virtual Guid Id { get; private set;}
    public virtual string Name { get; set; }
    public virtual string Description { get; set; }
    public virtual IList<RightHeader> AllowedRights { get; set; }
    public virtual IList<RightHeader> DeniedRights { get; set; }
    public virtual IList<RightHeader> UnsetRights { get; set; }
}

public class RightHeader
{
    public virtual decimal Num { get; private set; }
    public virtual string Name { get; set; }
    public virtual string Description { get; set; }
}

public class GroupHeaderMap : ClassMap<GroupHeader>
{
    public GroupHeaderMap()
    {
        Table("GROUP_HEADER");
        Id(x => x.Id, "GROUP_ID");
        Map(x => x.Name, "GROUP_NAME").Unique();
        Map(x => x.Description, "GROUP_DESCRIPTION");

        HasManyToMany(x => x.AllowedRights)
            .Table("GROUP_RIGHT_COMPOSITE")
            .ParentKeyColumn("GROUP_ID")
            .ChildKeyColumn("RIGHT_NUM")
            .Where("RIGHT_VALUE = 1")
            .Cascade.SaveUpdate();

        HasManyToMany(x => x.DeniedRights)
            .Table("GROUP_RIGHT_COMPOSITE")
            .ParentKeyColumn("GROUP_ID")
            .ChildKeyColumn("RIGHT_NUM")
            .Where("RIGHT_VALUE = -1")
            .Cascade.SaveUpdate();

        HasManyToMany(x => x.UnsetRights)
            .Table("GROUP_RIGHT_COMPOSITE")
            .ParentKeyColumn("GROUP_ID")
            .ChildKeyColumn("RIGHT_NUM")
            .Where("RIGHT_VALUE = 0")
            .Cascade.SaveUpdate();
    }
}

public class RightHeaderMap : ClassMap<RightHeader>
{
    public RightHeaderMap()
    {
        Table("RIGHT_HEADER");
        Id(x => x.Num, "RIGHT_NUM");
        Map(x => x.Name, "RIGHT_NAME");
        Map(x => x.Description, "RIGHT_DESCRIPTION");
    }
}

目前,每当我创建一个新的GroupHeader并填充AllowedRights成员变量时,它都无法插入这些记录,因为GROUP-RIGHT-COMPOSITE中的RIGHT-VALUE列不允许为空。我真的不知道如何用流利的语言来映射,也不知道在我的实体中应该如何处理。任何帮助都将不胜感激。