docs: public static BackoffStrategy linearBackoff(long initialSleepTime, TimeUnit initialSleepTimeUnit,
                                                  long increment, TimeUnit incrementTimeUnit) {
          Preconditions.checkNotNull(initialSleepTimeUnit, "The initial wait time unit may not be null");
          Preconditions.checkNotNull(incrementTimeUnit, "The increment time unit may not be null");
          return new LinearBackoffStrategy(initialSleepTimeUnit.toMillis(initialSleepTime),
                  incrementTimeUnit.toMillis(increment));
      }