title: EFCore BulkInsert with one to one relationship
body: <p>I'm trying to use bulkinsert from EFCore.BulkExtensions in .NET Core 2.1 with one to one relationships. I have 2 Database Entities</p>
  
  <pre><code>public partial class Entity1
  {
      public int ID { get; set; }
      public virtual Entity2 Entity2Obj { get; set; }
  }
  
  public partial class Entity2 
  {
      public int ID { get; set; }
      public int Entity1_ID{ get; set; }
      public virtual Entity1 Entity1Obj { get; set; }
  }
  </code></pre>
  
  <p>Then I insert a list of Entity1 Items</p>
  
  <pre><code> _context.BulkInsert(Entity1ItemsList);
  </code></pre>
  
  <p>This only works and inserts Entity1 objects in my database. The associated Entity2  items are not inserted. Is there a way to achieve that?</p>
  
  <p>The navigation properties are automatically created during Scaffold-DbContext (database first)</p>
  
  <pre><code>entity.HasOne(d =&gt; d.Entity1 )
      .WithOne(p =&gt; p.Entity2)
      .HasForeignKey&lt;Entity2&gt;(d =&gt; d.Entity1_ID)
      .OnDelete(DeleteBehavior.ClientSetNull)
      .HasConstraintName("FK_Entity1_Entity2");
  </code></pre>