MySQL NHibernate how to use composite indicator?

Question

MySQL

I have such a table

. I try to map it like this .., you can’t change it (table).

using FluentNHibernate.Mapping;
using Sourcedb.Entities;
 
namespace Sourcedb.Mapping
{
    public class OptionsMap : ClassMap<Options>
    {
        public OptionsMap()
        {
            Table("s_options");
            
            CompositeId()
                .KeyProperty(x => x.Productid, "product_id")
                .KeyProperty(x => x.Fiature, "feature_id")
                .KeyProperty(x => x.Val, "value");
        }
    }
}

But I get a crash at startup, I can’t understand what he doesn’t like and how to fix it?