title: WebAPI 2.2 does not support substringof function
body: <p>I've a WebAPI 2.2 service with OData support.</p>
  
  <p>My controller has an action which returns an <code>IQuerable&lt;Entity&gt;</code>, but I'm unable to use <code>$filter=substringof</code> function even if I allow all functions.</p>
  
  <pre><code>[Authorize]
  public class MyController : ODataController
  {
      [EnableQuery(AllowedFunctions=AllowedFunctions.All)]
      public IQueryable&lt;Entity&gt; GetEntities()
      {
        return GetMyQueryable();
      }
  }
  </code></pre>
  
  <p>When I hit a URL like <code>http://localhost:49844/Entities/?$filter=substringof('Queen',Name)</code></p>
  
  <p>I get an error saying substringof is not allowed.</p>
  
  <pre><code>{
  "error": {
      "code": "",
      "message": "The query specified in the URI is not valid. An unknown function with name 'substringof' was found. This may also be a function import or a key lookup on a navigation property, which is not allowed.",
      "innererror": {
          "message": "An unknown function with name 'substringof' was found. This may also be a function import or a key lookup on a navigation property, which is not allowed.",
          "type": "Microsoft.OData.Core.ODataException",
  </code></pre>
  
  <p>Any idea why I might be seeing this error?</p>