title: Provisioned throughput collection should have a partition key error when creating partitionless collection
body: <p>I created a document db database with RU shared at DB level rather than at container level. Is it possible to create a collection without partition under the same DB? When I try to do the same with the code below I get an error</p>
  
  <blockquote>
    <p>Provisioned throughput collection should have a partition key</p>
  </blockquote>
  
  <pre><code>private async Task CreatePartitionLessCollection()
  {
      try
      {
          DocumentClient documentClient = new DocumentClient(new Uri(EndpointUrl), PrimaryKey);
          DocumentCollection myCollection = new DocumentCollection();
          myCollection.Id = "MyCollection";
          await documentClient.CreateDocumentCollectionAsync(
                  UriFactory.CreateDatabaseUri("MyDB"), myCollection, new RequestOptions { OfferThroughput = 400 });
      }
      catch (Exception ex)
      {
          Console.WriteLine(ex.GetBaseException().Message);
      }
   }
  </code></pre>