title: LINQ Query Issue with using Any on DocumentDB for child collection
body: <p>Using v1.8 .Net SDK</p>
  
  <p>Trying return Sales where the Sale client array contains the Client ID I’m looking for.</p>
  
  <pre><code>Sales.Where(sale =&gt; sale.Clients.Any(c =&gt; c.ClientId == clientID));
  </code></pre>
  
  <p>Returns Error
  "Nullable object must have a value."</p>
  
  <p>at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
  at System.Threading.Tasks.Task<code>1.GetResultCore(Boolean waitCompletionNotification)
  at System.Threading.Tasks.Task</code>1.get_Result()
  at Microsoft.Azure.Documents.Linq.DocumentQuery<code>1.GetEnumerator()
  at System.Collections.Generic.List</code>1..ctor(IEnumerable<code>1 collection)
  at System.Linq.Enumerable.ToList[TSource](IEnumerable</code>1 source)</p>
  
  <p>ClientID is a GUID, but trying to query any property on the client object returns the same error.</p>
  
  <p>If I run the same query on the same data but just using a List collection (i.e. not using DocumentDB) then all is fine.</p>
  
  <p>Any advice appreciated.
  Thanks</p>