Why a new migration on making a property virtual? - entity-framework

Question

I had entities such as this:
public class Foo
{
public int Id { get; set; }
public Bar Bar { get; set; }
public Bar2 Bar2 { get; set; }
}
public class Bar
{
public int Id { get; set; }
public string Description { get; set; }
}
public class Bar2
{
public int Id { get; set; }
public string Description { get; set; }
}
which migrations are:
CreateTable(
"dbo.Bar",
c => new
{
Id = c.Int(nullable: false, identity: true),
Description = c.String(),
})
.PrimaryKey(t => t.Id);
CreateTable(
"dbo.Bar2",
c => new
{
Id = c.Int(nullable: false, identity: true),
Description = c.String(),
})
.PrimaryKey(t => t.Id);
CreateTable(
"dbo.Foo",
c => new
{
Id = c.Int(nullable: false, identity: true),
Bar_Id = c.Int(),
Bar2_Id = c.Int(),
})
.PrimaryKey(t => t.Id)
.ForeignKey("dbo.Bar", t => t.Bar_Id)
.ForeignKey("dbo.Bar2", t => t.Bar_Id)
.Index(t => t.AlertCause_Id)
then I set a Bar property at Foo as virtual and it breaks with "AutomaticMigrationsDisabledException: Unable to update database to match the current model because there are pending changes and automatic migration is disabled." And after the migration re-scaffolding the code changes only in that Bar_Id becomes BarId but for Bar2 it remains Bar2_Id. So I wonder why it gets me the migration re-scaffolded if it seems it does not change anything? Yes it needs the proxy classes and lazy load, etc. but why a new migration? Thanks!
UPDATE
I've missed that the migration was actually triggered by the adding of a foreign key property, BarId. So my mistake here.

Answer 1

Found the reason. This is an incorrect question as the migration was triggered because of the adding a reference property (BarID). My mistake. So closing it.