private DateTime providedOrDefaultFromValue(DateTime from, DateTime to, AggregateCountResolution resolution) {
		if (from != null) {
			return from;
		}
		switch (resolution) {
			case minute:
				return to.minusMinutes(59);
			case hour:
				return to.minusHours(23);
			case day:
				return to.minusDays(6);
			case month:
				return to.minusMonths(11);
			case year:
				return to.minusYears(4);
			default:
				throw new IllegalStateException("Shouldn't happen. Unhandled resolution: " + resolution);
		}
	}
Return a default value for the interval start if none has been provided.
spring-xd-dirt/src/main/java/org/springframework/xd/dirt/rest/metrics/AggregateCountersController.java