void stop() {
    executor.shutdown();
    logger.info("Stopped watching {}", path);
  }
Watches a single file for changes by polling the last modified time on the file.

<p>
Note: {@link WatchService} is not used here because it has problems with container file systems
and remote file systems.
<p>
geode-core/src/main/java/org/apache/geode/internal/net/filewatch/PollingFileWatcher.java