code: public RetryTemplateBuilder exponentialBackoff(long initialInterval,
  			double multiplier, long maxInterval) {
  		return exponentialBackoff(initialInterval, multiplier, maxInterval, false);
  	}
docs: Use exponential backoff policy. The formula of backoff period:
  <p>
  {@code currentInterval = Math.min(initialInterval * Math.pow(multiplier, retryNum), maxInterval)}
  <p>
  (for first attempt retryNum = 0)
  @param initialInterval in milliseconds
  @param multiplier see the formula above
  @param maxInterval in milliseconds
  @return this
  @see ExponentialBackOffPolicy