title: Unable to determine the principal end of an association between the types
body: <p>I'm getting this error: </p>
  
  <blockquote>
    <p>Unable to determine the principal end of an association between the
    types CustomerDetail and Customer.</p>
  </blockquote>
  
  <p>Here is my <code>Customer</code> and <code>CustomerDetail</code> models</p>
  
  <pre><code>[Table("CUSTOMER")]
  public class Customer
  {
      [Required]
      [Column("CUSTOMER_ID")]
      public int Id {get; set;}
  
      [Column("FIRST_NAME")]
      public string FirstName {get; set;}
      // other fields  
  
      public virtual CustomerDetail customerDetail {get; set;}
  }
  
  [Table("CUSTOMER_DETAIL")]
  public class CustomerDetail
  {
      [Required]
      [Column("CUSTOMER_DETAIL_ID")]
      public int Id {get; set;}
      // other fields
  
      public virtual Customer Customer {get; set;} 
  }
  </code></pre>
  
  <p><code>Customer</code> to <code>CustomerDetail</code> has a 1:1 relation. </p>