code: private Observable<ShutdownStatus> wrapBestEffortShutdown(Observable<Boolean> source, final String target) {
          return wrapShutdown(source, target)
                  .map(new Func1<ShutdownStatus, ShutdownStatus>() {
                      @Override
                      public ShutdownStatus call(ShutdownStatus original) {
                          if (original.cause == null && !original.success) {
                              LOGGER.info(target + " shutdown is best effort, ignoring failure");
                              return new ShutdownStatus(target, true, null);
                          } else {
                              return original;
                          }
                      }
                  });
      }
docs: This method wraps an Observable of Boolean (for shutdown hook) into an Observable of ShutdownStatus.
  It will log each status with a short message indicating which target has been shut down, and the result of
  the call.
  Additionally it will ignore signals that shutdown status is false (as long as no exception is detected), logging that the target is "best effort" only.