An employee may have a department to which he belongs. A department has employees who belong to it, and there may be an employee who is the head of this department.

public class Employee
{
    public string Id { get; set; } = null!;
 
    public int? DepartmentId { get; set; }
    public virtual Department? Department { get; set; }
}
 
public class Department
{
    public int Id { get; set; }
 
    public virtual ObservableCollection<Employee> Employees { get; set; } = new();
 
    public string? DepartmentHeadId { get; set; }
    public virtual Employee? DepartmentHead { get; set; }
}
 
public class DepartmentMap : IEntityTypeConfiguration<Department>
{
    public void Configure(EntityTypeBuilder<Department> builder)
    {
        ...
 
        builder.HasMany(d => d.Employees).WithOne(e => e.Department).HasForeignKey(e => e.DepartmentId);
 
        builder.HasOne(d => d.DepartmentHead).WithOne().HasForeignKey<Department>(d => d.DepartmentHeadId);
    }
}

Application starts but in the logs it writes:

dbug: `CoreEventId.MultipleNavigationProperties`[10607] (Microsoft.EntityFrameworkCore.Model)
No relationship from 'Department' to 'Employee' has been configured by convention because there are multiple properties on one entity type - {'DepartmentHead', 'Employees'} that could be matched with the properties on the other entity type - {'Department'}. This message can be disregarded if explicit configuration has been specified in 'OnModelCreating'.

dbug: `CoreEventId.MultipleNavigationProperties`[10607] (Microsoft.EntityFrameworkCore.Model)
No relationship from 'Employee' to 'Department' has been configured by convention because there are multiple properties on one entity type - {'Department'} that could be matched with the properties on the other entity type - {'DepartmentHead', 'Employees'}. This message can be disregarded if explicit configuration has been specified in 'OnModelCreating'.

dbug: `CoreEventId.MultipleNavigationProperties`[10607] (Microsoft.EntityFrameworkCore.Model)
No relationship from 'Employee' to 'Department' has been configured by convention because there are multiple properties on one entity type - {'Department'} that could be matched with the properties on the other entity type - {'DepartmentHead', 'Employees'}. This message can be disregarded if explicit configuration has been specified in 'OnModelCreating'.

dbug: `CoreEventId.MultipleNavigationProperties`[10607] (Microsoft.EntityFrameworkCore.Model)
No relationship from 'Department' to 'Employee' has been configured by convention because there are multiple properties on one entity type - {'DepartmentHead', 'Employees'} that could be matched with the properties on the other entity type - {'Department'}. This message can be disregarded if explicit configuration has been specified in 'OnModelCreating'.

dbug: `CoreEventId.MultipleNavigationProperties`[10607] (Microsoft.EntityFrameworkCore.Model)
No relationship from 'Employee' to 'Department' has been configured by convention because there are multiple properties on one entity type - {'Department'} that could be matched with the properties on the other entity type - {'DepartmentHead', 'Employees'}. This message can be disregarded if explicit configuration has been specified in 'OnModelCreating'.