code: public static ForkJoinPool getPool() {
          Thread t = Thread.currentThread();
          return (t instanceof ForkJoinWorkerThread) ?
              ((ForkJoinWorkerThread) t).pool : null;
      }
docs: Returns the pool hosting the current task execution, or null
  if this task is executing outside of any ForkJoinPool.
  
  @see #inForkJoinPool
  @return the pool, or {@code null} if none