Structural structure of the object with a ratio of 1 to 1 at both ends

Question

Structural structure of the object with a ratio of 1 to 1 at both ends

Most of the questions I found were not what I was looking for.

I have 2 tables:

public class User
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public Guid UserId { get; set; }

    public Guid? CustomerId { get; set; }

    [ForeignKey("CustomerId")]
    public Customer Customer { get; set; }
}

public class Customer
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public Guid CustomerId { get; set; }

    public Guid? UserId { get; set; }

    [ForeignKey("UserId")]
    public User User { get; set; }
}

A Usercan exist without a Customer, and a Customercan exist without User.

I tried the free API as follows:

modelBuilder.Entity<Customer>()
    .HasOptional<User>(c => c.User)
    .WithOptionalDependent(c => c.Customer)
    .Map(c => c.MapKey("UserId"));

But he keeps giving me this error when I try to create a migration:

Customer_User_Source: : Multiplicity is not valid in Role 'Customer_User_Source' in relationship 'Customer_User'. Because the Dependent Role properties are not the key properties, the upper bound of the multiplicity of the Dependent Role must be '*'.

Update

I changed my model to this:

public class User
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public Guid UserId { get; set; }

    public virtual Customer Customer { get; set; }
}

public class Customer
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public Guid CustomerId { get; set; }

    public virtual User User { get; set; }
}

With full API:

modelBuilder
    .Entity<Customer>()
    .HasOptional(l => l.User)
    .WithOptionalPrincipal()
    .Map(k => k.MapKey("CustomerId"));

modelBuilder
    .Entity<User>()
    .HasOptional(c => c.Customer)
    .WithOptionalPrincipal()
    .Map(k => k.MapKey("UserId"));