title: No properties are mapped for type using csvHelper
body: <p>I have two methods that return list of EmployeeCsv and CardCsv.</p>
  <pre><code>public class EmployeeCsv
  {
      public string EmployeeId { get; set; }
      public string EmployeeName { get; set; }
  }
  
  public class CardCsv
  {
      public string MaxCharge { get; set; }
      public string MaxDiscount { get; set; }
  }
  
  public List&lt;EmployeeCsv&gt; GetEmployeeList() {} // returns list of EmployeeCsv
  public List&lt;CardCsv&gt; GetCardList() {} // returns list of CardCsv
  </code></pre>
  <p>I wanted to declare one type list for those two methods.
  So I changed them like below</p>
  <pre><code>public interface ITest {}
  public class EmployeeCsv : ITest
  {
      public string EmployeeId { get; set; }
      public string EmployeeName { get; set; }
  }
  
  public class CardCsv : ITest
  {
      public string MaxCharge { get; set; }
      public string MaxDiscount { get; set; }
  }
  
  public List&lt;ITest&gt; GetEmployeeList() {}
  public List&lt;ITest&gt; GetCardList() {}
  </code></pre>
  <p>Main:</p>
  <pre><code>void main()
  {
      var records = new List&lt;ITest&gt;();
      records = GetEmployeeList();
      using (var writer = new StreamWriter(fileName))
      using (var csv = new CsvWriter(writer, CultureInfo.InvariantCulture))
      {
          csv.Configuration.ShouldQuote = (field, context) =&gt; true;
          csv.WriteRecords(records); // error here
      }
  }
  </code></pre>
  <p>I get an error on saving after adding interface to those two classes.
  How can I fix this?</p>