Navigation property combined with backing field leads to errors OnModelCreating

[APIWT]

Take the following entities:

public sealed class Employee
{
    private Supervisor supervisor;

    public long Id { get; set; }

    public long? SupervisorId { get; set; }

    public Supervisor Supervisor
    {
        get => this.Department?.Supervisor ?? this.supervisor;
        set => this.supervisor = value;
    }

    public long? DepartmentId { get; set; }

    public Department Department { get; set; }
}

public sealed class Department
{
	public long Id { get; set; }
	
    public long? SupervisorId { get; set; }

    public Supervisor Supervisor { get; set;}
}

And the following DB context:

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

    public DbSet<Employee> Employee { get; set; }
    public DbSet<Supervisor> Supervisor { get; set; }
    public DbSet<Department> Department { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        modelBuilder.Entity<Employee>()
            .Property(e => e.Supervisor)
            .HasField("supervisor")
            .UsePropertyAccessMode(PropertyAccessMode.Field);
    }
}

When running the update database command:

dotnet tool run dotnet-ef database update

The following error is generated:

The property 'Employee.Supervisor' is of type 'Supervisor' which is not supported by current database provider. Either change the property CLR type or ignore the property using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'.

How do I combine both the backing field concept and the navigation property concept?

Further technical details

EF Core version: 3.1.2
Database provider: (e.g. Microsoft.EntityFrameworkCore.SqlServer)
Target framework: (e.g. .NET Core 3.1)

[APIWT]

Just in-case this is not a bug, and I am doing something wrong, I have created a Stackoverflow post for additional feedback: https://stackoverflow.com/questions/60619040/in-entityframework-core-is-it-possible-to-use-a-navigation-property-combined-wi

[ajcvickers]

@APIWT The answer to this depends on whether or not Supervisor is intended to be an entity type or not. If it is, then the references to it are "navigation properties" which are not configured using the Property API. See #6674 for how to configure the backing field.

If it's not an entity type, then use a value converter to map it to the database.

[APIWT]

Hey @ajcvickers. Supervisor is intended to be an entity type. I'll check out your link. Thanks!

[APIWT]

I'm going to close this issue, but I would recommend pointing out this information formally in the documentation. Thank you!