title: Contains filter on Microsoft Graph query not working
body: <p>I'm trying to user the <em>contains</em> filter on a /users query, like this for example:
  <a href="https://graph.microsoft.com/v1.0/users" rel="noreferrer">https://graph.microsoft.com/v1.0/users</a>?$filter=contains(displayName, 'Garth')</p>
  
  <p>However, this results in a <em>BadRequest</em> response saying "An unknown function with name 'contains' was found. This may also be a key lookup on a navigation property, which is not allowed."</p>
  
  <p>According to the OData 4.0 specs, the contains filter should be available though. Is there a way to use a contains filter on a list of users?</p>