Program: 11643
Project: 11643
Buggy source:
public static void init(){
  if (!init.compareAndSet(false,true))   return;
  String userDir=System.getProperty("String_Node_Str");
  logger=Logger.get("String_Node_Str");
  iconPath=Paths.get("String_Node_Str");
  try {
    loadIcon();
  }
 catch (  IOException ex) {
    logger.log("String_Node_Str");
  }
  Thread watcherThread=new Thread(() -> {
    try {
      Path dir=Paths.get(userDir);
      WatchService service=dir.getFileSystem().newWatchService();
      WatchKey watchKey=dir.register(service,ENTRY_CREATE,ENTRY_MODIFY,ENTRY_DELETE);
      while (true) {
        try {
          WatchKey eventKey=service.take();
          logger.log("String_Node_Str");
          if (eventKey != watchKey) {
            logger.warn(String.format("String_Node_Str",eventKey,watchKey));
            break;
          }
          eventKey.pollEvents().forEach(e -> {
            if (!e.context().equals(iconPath))             return;
            logger.log("String_Node_Str" + e.kind());
            if (e.kind() == ENTRY_CREATE || e.kind() == ENTRY_MODIFY) {
              try {
                loadIcon();
              }
 catch (              IOException ex) {
                ex.printStackTrace();
              }
            }
 else             if (e.kind() == ENTRY_DELETE) {
              b64icon.set(null);
            }
          }
);
          if (!eventKey.reset()) {
            logger.log("String_Node_Str");
            break;
          }
        }
 catch (        InterruptedException ex) {
          ex.printStackTrace();
          break;
        }
      }
    }
 catch (    IOException e) {
      e.printStackTrace();
    }
  }
,"String_Node_Str");
  watcherThread.setDaemon(true);
  watcherThread.start();
}

Fixed version (ground truth):
public static void init(){
  if (!init.compareAndSet(false,true))   return;
  try {
    loadIcon();
  }
 catch (  IOException ex) {
    logger.log("String_Node_Str");
  }
  String userDir=System.getProperty("String_Node_Str");
  Thread watcherThread=new Thread(() -> {
    try {
      Path dir=Paths.get(userDir);
      WatchService service=dir.getFileSystem().newWatchService();
      WatchKey watchKey=dir.register(service,ENTRY_CREATE,ENTRY_MODIFY,ENTRY_DELETE);
      while (true) {
        try {
          WatchKey eventKey=service.take();
          logger.log("String_Node_Str");
          if (eventKey != watchKey) {
            logger.warn(String.format("String_Node_Str",eventKey,watchKey));
            break;
          }
          eventKey.pollEvents().forEach(e -> {
            if (!e.context().equals(iconPath))             return;
            logger.log("String_Node_Str" + e.kind());
            if (e.kind() == ENTRY_CREATE || e.kind() == ENTRY_MODIFY) {
              try {
                loadIcon();
              }
 catch (              IOException ex) {
                ex.printStackTrace();
              }
            }
 else             if (e.kind() == ENTRY_DELETE) {
              b64icon.set(null);
            }
          }
);
          if (!eventKey.reset()) {
            logger.log("String_Node_Str");
            break;
          }
        }
 catch (        InterruptedException ex) {
          ex.printStackTrace();
          break;
        }
      }
    }
 catch (    IOException e) {
      e.printStackTrace();
    }
  }
,"String_Node_Str");
  watcherThread.setDaemon(true);
  watcherThread.start();
}