title: Reflection, get DataAnnotation attributes from buddy class
body: <p>I need to check if property has specific attribute defined in its buddy class:</p>
  
  <pre><code>[MetadataType(typeof(Metadata))]
  public sealed partial class Address
  {
      private sealed class Metadata
      {
          [Required]
          public string Address1 { get; set; }
  
          [Required]
          public string Zip { get; set; }
      }
  }
  </code></pre>
  
  <p>How to check what properties has defined <code>Required</code> attribute?</p>
  
  <p>Thank you.</p>