public class Document
{
    public ObjectId Id { get; set; }
}

[Test]
public void InjectGenericQueryBuilder()
{
    var doc = _collection.AsQueryable<Document>().SingleOrDefault(x => Query<Document>.EQ(y => y.Id, ObjectId.Empty).Inject());
}

The following exception is thrown when this unit test is run:

System.ArgumentException : Unsupported where clause: LinqToMongo.Inject...

This is true for pretty much any Inject done using generic query builder.

Note that the non-generic query builder (where field name is specified as magic string) works fine.