docs: public static Delay exponential(long lower, long upper, TimeUnit unit, int powersOf) {
  
          LettuceAssert.isTrue(lower >= 0, "Lower boundary must be greater or equal to 0");
          LettuceAssert.isTrue(upper > lower, "Upper boundary must be greater than the lower boundary");
          LettuceAssert.isTrue(powersOf > 1, "PowersOf must be greater than 1");
          LettuceAssert.notNull(unit, "TimeUnit must not be null");
  
          return exponential(Duration.ofNanos(unit.toNanos(lower)), Duration.ofNanos(unit.toNanos(upper)), powersOf, unit);
      }