How To Write Automapping Convention That Uses Sequence

I'm with updating some of our mappings from the fluent mapping paradigm to the auto mapping paradigm. I have a class named Group where the current fluent mapping for the identity column looks like this:

Id(x => x.Id, "ID")
    .GeneratedBy
    .Native("GROUPS_SEQ");

Resulting in HBM that looks like this:

<id name="Id" type="System.Int64, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
  <column name="ID" />
  <generator class="native">
    <param name="sequence">GROUPS_SEQ</param>
  </generator>
</id>

This works great with our Oracle database AND with tests that use SQLite. Unfortunately I can't figure out how to create an IIdConvention convention that will give me the same result. I've gotten this far:

public class PrimaryKeyConvention : IIdConvention
{
    public void Apply(FluentNHibernate.Conventions.Instances.IIdentityInstance instance)
    {
        string pluralized = Inflector开发者_如何学Python.Net.Inflector.Pluralize(instance.EntityType.Name);
        string underscored = Inflector.Net.Inflector.Underscore(pluralized);
        string uppercased = underscored.ToUpper();

        string sequenceName = string.Format("{0}_SEQ", uppercased);

        instance.Column("Id");
        instance.UnsavedValue("0");
        instance.GeneratedBy.Native(sequenceName);
    }
}

Unfortunately the last line causes a compile error because the .Native method doesn't accept a sequence name string like it does in the fluent mappings. Does anyone have any suggestions on how best to solve this?

Thanks!

The GeneratorInstance.cs file already contains implementations for the following methods:

void Native(string sequenceName);
void Native(string sequenceName, Action<ParamBuilder> paramValues);

The methods are not exposed in the IGeneratorInstance.cs interface. I went ahead and added them which allowed me to create the primary key convention that I need. As near as I can tell they work fine. Unfortunately my company's IT security group has seen fit to close a bunch of ports on their firewall which prevents me from contributing this back via github. So if anyone wants to submit the update for me I would appreciate it.

Thanks!