With wrapping collector scenarios, wrapping LeafCollector needs access to wrapped LeafCollector.
If wrapping LeafCollector has access to LeafReaderContext, it seems one can use getLeafCollector "getter" anytime to get the wrapped leaf collector. if collect(int doc) method retrieves LeafCollector on every call, this does not work since getLeafCollector behaves more like a prototype factory. Question: If I am writing a new Collector, is it fair to assume getLeafCollector will be called only once per segment.
