code: public Retryer<R> incrementingWait(long initialSleepTime, 
              TimeUnit initialSleepUnit, long increment, TimeUnit incrementUnit) {
          return incrementingWait(checkNotNull(initialSleepUnit).toMillis(initialSleepTime), 
                         checkNotNull(incrementUnit).toMillis(increment));
      }
docs: Sets the strategy that sleeps a fixed amount of time after the first
  failed attempt and in incrementing amounts of time after each additional failed attempt.
  
  @param initialSleepTime
  @param initialSleepUnit
  @param increment
  @param incrementUnit
  @return