}
            };
        }
    }

    abstract class CollectingFileVisitor implements FileVisitor<Path> {
        protected final Collector collector;

        public CollectingFileVisitor(Collector collector) {
            this.collector = collector;
            collector.recordVisitHierarchy();
        }

        @Override

            public boolean test(String element) {
                return element.startsWith(start);
            }
        }
    }

    private static class PathVisitor extends DirectorySnapshotterStatistics.CollectingFileVisitor {
        private final RelativePathTracker pathTracker = new RelativePathTracker();
        private final FilteredTrackingMerkleDirectorySnapshotBuilder builder;