output: #fixed code
                                  public void shutdown() {
          log.info("ok, shutting down ...");
          if (lock == null) {
              _shutdown();
          }
          else {
              synchronized (lock) {
                  lock.notify();
              }
          }
      }
input: #vulnerable code 
                                  public void shutdown() {
          log.info("ok, shutting down ...");
          synchronized (lock) {
              lock.notify();
          }
      } 
                              #location 2 
                              #vulnerability type THREAD_SAFETY_VIOLATION