code: public static <V> Action1<TaskContext<V>> fixedWait(long sleepTime, TimeUnit timeUnit) {
          return ctx -> ThreadUtils.sleep(sleepTime, timeUnit);
      }
docs: The fixed sleep time.
  
  @param sleepTime The sleep time.
  @param timeUnit  The time unit.
  @param <V>       The return value type.
  @return The wait strategy action.