OwnsOne drops IDENTITY from tables key

I have created a order entity and right now I have a Money type which I want to include it in my Order entity as an Own type.

public class Money
{
    public decimal Value { get; set; }

    public Currency Currency { get; set; }
}

and my Order class is like the following

public class Order
{
   [Key]
   public long OrderId { get; set; }
}

now I want to add a money type to order entity like the following:

public class Order
{
    [Key]
    public long OrderId { get; set; }
    public Money Amount { get; set; }
}

and the OrderContext looks like the following:

 protected override void OnModelCreating(ModelBuilder modelBuilder)
 {
     modelBuilder.Entity<Order>().OwnsOne(o => o.Amount);
 }

The issue happens when I run the entity framework migrations. This is what I get after running the migrations:

protected override void Up(MigrationBuilder migrationBuilder)
  {
      migrationBuilder.AlterColumn<long>(
          name: "OrderId",
          table: "Order",
          nullable: false,
          oldClrType: typeof(long),
          oldType: "bigint")
          .OldAnnotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn);

      migrationBuilder.AddColumn<int>(
          name: "Amount_Currency",
          table: "Order",
          nullable: true);

      migrationBuilder.AddColumn<decimal>(
          name: "Amount_Value",
          table: "Order",
          nullable: true);
  }

as you can see for some reason using OwnOne alters my OrderId column and when I check generated sql it looks like it drops the IDENTITY from it.

BEGIN
    IF NOT EXISTS(SELECT 1 FROM "__EFMigrationsHistory" WHERE "MigrationId" = '20200311224448_1.0.108-g5d3eec73db-Order') THEN
    ALTER TABLE `Order` ALTER COLUMN "OrderId" TYPE bigint;
    ALTER TABLE `Order` ALTER COLUMN "OrderId" SET NOT NULL;
    ALTER TABLE `Order` ALTER COLUMN "OrderId" DROP IDENTITY;
    ALTER TABLE `Order` ALTER COLUMN "OrderId" DROP DEFAULT;
    END IF;
END $$;

DO $$
BEGIN
    IF NOT EXISTS(SELECT 1 FROM "__EFMigrationsHistory" WHERE "MigrationId" = '20200311224448_1.0.108-g5d3eec73db-Order') THEN
    ALTER TABLE `Order` ADD "Amount_Currency" integer NULL;
    END IF;
END $$;

DO $$
BEGIN
    IF NOT EXISTS(SELECT 1 FROM "__EFMigrationsHistory" WHERE "MigrationId" = '20200311224448_1.0.108-g5d3eec73db-Order') THEN
    ALTER TABLE `Order` ADD "Amount_Value" numeric NULL;
    END IF;
END $$;

Does anybody know why adding an Owned type in Entity Framework and postgresql database causes this behavior and how can I make sure that the key field is not going to be altered?

• PostgreSQL 11.7
• Microsoft.AspNetCore.App 3.1.2
• Microsoft.NETCore.App 3.1.2
• Microsoft.EntityFrameworkCore.Design Version=3.1.1
• Npgsql.EntityFrameworkCore.PostgreSQL Version=3.1.2