code: public static Callable<Object> callable(final PrivilegedExceptionAction<?> action) {
          if (action == null)
              throw new NullPointerException();
          return new Callable<Object>() {
              public Object call() throws Exception { return action.run(); }};
      }
docs: Returns a {@link Callable} object that, when
  called, runs the given privileged exception action and returns
  its result.
  @param action the privileged exception action to run
  @return a callable object
  @throws NullPointerException if action null