Query against Link type in Google App Engine Datastore

Question

I'm trying to run a query to see if a link already exists in the database. In my example below url is of type Link.

Query query = pm.newQuery("select from com.ClassName where url == newUrl"); 
query.declareParameters("com.google.appengine.api.datastore.Link newUrl"); 
List<ResourceItem> results = (List<ResourceItem>) query.execute(newUrl);

When the code is executed, I get the following error:

"CreatorExpression defined with class of Url yet this class is not found"

Can you perform a query using the member of the class is of type Link? If so, how?