*
 * When the hierarchy is first registered via {@link #registerProbe(File)}, we don't yet create the probe.
 * That only happens when the hierarchy is actually read or written by Gradle, in which case
 * {@link #armWatchProbe(File)} is called.
 *
 * When the probe is armed, a probe file is created (or re-created) under the hierarchy.
 * This should cause a file system event to be produced by the operating system.

        return watchProbesByHierarchy.values().stream()
            .filter(WatchProbe::leftArmed)
            .map(WatchProbe::getWatchableHierarchy);
    }

    @Override
    public void armWatchProbe(File watchableHierarchy) {
        WatchProbe probe = watchProbesByHierarchy.get(watchableHierarchy);
        if (probe != null) {
            try {
                probe.arm();
            } catch (IOException e) {

                //noinspection ResultOfMethodCallIgnored
                probeDirectory.mkdirs();
                startWatchingProbeDirectory(probeDirectory);
                probeRegistry.armWatchProbe(probedHierarchy);
            });
    }

    protected abstract void updateWatchesOnChangedWatchedFiles(FileHierarchySet newWatchedFiles);