CollectionQueryInfo::notifyOfQuery is a non-static member function of CollectionQueryInfo, but it doesn't use any state from that class. It actually just gets an instance of CollectionIndexUsageTrackerDecoration from one of the parameters that was passed in, and calls a few member functions on it. It seems like there could instead just be a function CollectionIndexUsageTrackerDecoration::notifyOfQuery, or a free function somewhere notifyCollectionIndexUsageTrackerOfQuery - unless there's some reason this has to be on the CollectionQueryInfo