C＃NHibernate Joined-Subclass取得问题

    <class name=\"Company\" table=\"Company\">
        <id name=\"ID\" column=\"CompanyID\">
          <generator class=\"native\"/>
        </id>
        <joined-subclass name=\"CompanyAccounting\" table=\"company_accounting\" lazy=\"true\">
          <key column=\"CompanyID\"/>
        </joined-subclass>
        <joined-subclass name=\"CompanyCarbon\" table=\"company_carbon\" lazy=\"true\">
          <key column=\"CompanyID\" />
        </joined-subclass>
    </class>

        var company = CompanyAdapter.Get<Company>(_session, 32);
        Assert.IsNotNull(company);

        var client = CompanyAdapter.Get<CompanyClient>(_session, 32);
        Assert.IsNotNull(client);

        var client = CompanyAdapter.Get<CompanyClient>(_session, 32);
        Assert.IsNotNull(client);

        var company = CompanyAdapter.Get<Company>(_session, 32);
        Assert.IsNotNull(company);