Inheritance: Generated database model contains duplicate base properties

[MaStr11]

Steps to reproduce

I have a class hierarchy with three inheritance levels:

    public abstract class EditorOptionsBase
    {
        public EditorType EditorType { get; private set; }
        public bool ReadOnly { get; set; } = false;
    }

    public abstract class EditorOptionsText : EditorOptionsBase
    {
        public string Mask { get; set; }
    }

    public class EditorOptionsTextBox : EditorOptionsText
    {
    }

    public class EditorOptionsTextArea : EditorOptionsText
    {
        public int? MaxLength { get; set; }
    }

    public class EditorOptionsNumberBox : EditorOptionsText
    {
        public string Format { get; set; }
    }

    public class EditorOptionsCalendar : EditorOptionsBase
    {
    }

The model is configured like this

            var editorOptionsBase = modelBuilder.Entity<EditorOptionsBase>();
            editorOptionsBase.HasDiscriminator<EditorType>(nameof(EditorType)).
                HasValue<EditorOptionsNumberBox>(EditorType.dxNumberBox).
                HasValue<EditorOptionsTextBox>(EditorType.dxTextBox).
                HasValue<EditorOptionsTextArea>(EditorType.dxTextArea).
                HasValue<EditorOptionsCalendar>(EditorType.dxCalendar);

Expected:
There is only one Mask property created in the table:

Mask = table.Column<string>(nullable: true),

Actual:
Three properties are created:

Mask = table.Column<string>(nullable: true),
EditorOptionsTextArea_Mask = table.Column<string>(nullable: true),
EditorOptionsTextBox_Mask = table.Column<string>(nullable: true),

A complete sample project can be found here.

Remark
I was able to configure the model to do the right mapping like so:

modelBuilder.Entity<EditorOptionsTextBox>().Property(eotb => eotb.Mask).HasColumnName(nameof(EditorOptionsText.Mask));

But this doesn't scale because it needs to be repeated for each concrete type.

Further technical details

EF Core version: 2.1.4
Database Provider: Microsoft.EntityFrameworkCore.SqlServer
Operating system: Win 10 x64
IDE: Visual Studio 2017 15.9.1

[ajcvickers]

Note for triage: If Mask is on the base type, then we get only one column. When it's on a middle type of the hierarchy, it seems like any derived types from this middle type should also only get one column.

@MaStr11 A slightly better workaround is to bulk-update the model at the end of OnModelCreating. Something like:

foreach (var entityType in modelBuilder.Model.GetEntityTypes()
    .Where(e => typeof(EditorOptionsText).IsAssignableFrom(e.ClrType)))
{
    entityType
        .FindProperty(nameof(EditorOptionsText.Mask))
        .Relational()
        .ColumnName = nameof(EditorOptionsText.Mask);
}

[ajcvickers]

Note from triage: EditorOptionsText is not mapped.

[AndriySvyryd]

Related to #12963 and #10446