title: How to make a Property nullable in web api
body: <p>For a model file which looks like:</p>
  
  <pre><code>public class WebApiEntity
  {
    public string id { get; set; }
    public Collection&lt;CData&gt; data { get; set; }
  }
  
  
  public class CData
  {
    public string CType { get; set; }
  
    public string CId { get; set; }
  }
  </code></pre>
  
  <p>When I generate an ODATA client using service reference, it looks something like:</p>
  
  <pre><code>&lt;EntityType Name="WebApiEntity"&gt;
      &lt;Key&gt;
      &lt;PropertyRef Name="id" /&gt;
      &lt;/Key&gt;
      &lt;Property Name="id" Type="Edm.String" Nullable="false" /&gt;
      &lt;Property Name="data" Type="Collection(NamespaceValue.CData)" Nullable="false" /&gt;
  &lt;/EntityType&gt;
  </code></pre>
  
  <p>It has nullable property set to FALSE. What do I have to do to set it to TRUE.
  It seems Nullable&lt;> can't be used here. Appreciate any help here. </p>