Cosmos owned types expose separate __jObject shadow property

[JoasE]

Bug description

A _jObject shadow property is created for owned types, while it should only be for entity/document root -types.
See: #37322 (comment) for more details

Your code

using var context = new Context(
    new DbContextOptionsBuilder()
    .UseCosmos("AccountEndpoint=https://localhost:8081/;AccountKey=C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw==", "Testing")
    .ConfigureWarnings(x => x.Throw(CoreEventId.ConflictingShadowForeignKeysWarning))
    .Options);

await context.Database.EnsureDeletedAsync();
await context.Database.EnsureCreatedAsync();

var entity = new Entity
{
    Id = Guid.NewGuid(),
    OwnedType = new OwnedType
    {
        Id = Guid.NewGuid(),
        Name = "Test"
    }
};

context.Add(entity);
await context.SaveChangesAsync();

Console.WriteLine("Added");
Console.WriteLine(context.Entry(entity).Property<JObject>("__jObject").CurrentValue); // not null
Console.WriteLine(context.Entry(entity.OwnedType).Property<JObject>("__jObject").CurrentValue); // null
Console.WriteLine("");

context.ChangeTracker.Clear();

entity = await context.Set<Entity>().Where(x => x.Id == entity.Id).FirstAsync();
Console.WriteLine("Added retrieved");
Console.WriteLine(context.Entry(entity.OwnedType).Property<JObject>("__jObject").CurrentValue); // not null

public class Context : DbContext
{
    public Context(DbContextOptions options) : base(options)
    {
    }

    protected Context()
    {
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Entity>(entity =>
        {
            entity.Property(x => x.Id);
            entity.OwnsOne(x => x.OwnedType);
        });
    }
}

public class Entity
{
    public Guid Id { get; set; }

    public string Name { get; set; }

    public OwnedType OwnedType { get; set; }
}


public class OwnedType
{
    public Guid Id { get; set; }

    public string Name { get; set; }
}

EF Core version

10.0.0

Database provider

Microsoft.EntityFrameworkCore.Cosmos

Target framework

.NET 10

Operating system

Windows 11

IDE

VS 2026