code: public static boolean isFixedRate(final Object task) {
  
          if (task instanceof Task) {
              final Task ltask = (Task) task;
  
              return (ltask.relative && ltask.period > 0);
          } else {
              return false;
          }
      }
docs: Retrieves whether the specified argument references a task scheduled
  periodically using fixed rate scheduling.
  
  @param task a task reference
  @return true if the task is scheduled at a fixed rate