Refactor roll forward in CronField

Before this commit, CronField.Type::rollForward added temporal units
to reach the higher order field. This caused issues with DST, where
the added amount of hours was either too small or too large.

This commit refactors the implementation so that it now adds one to the
higher order field, and reset the current field to the minimum value.

Closes spring-projectsgh-28095

Author: poutsma

spring-context/src/main/java/org/springframework/scheduling/support/CronField.java

@@ -18,6 +18,7 @@
 
 import java.time.DateTimeException;
 import java.time.temporal.ChronoField;
+import java.time.temporal.ChronoUnit;
 import java.time.temporal.Temporal;
 import java.time.temporal.ValueRange;
 import java.util.function.BiFunction;
@@ -168,22 +169,25 @@ protected static <T extends Temporal & Comparable<? super T>> T cast(Temporal te
 	 * day-of-month, month, day-of-week.
 	 */
 	protected enum Type {
-		NANO(ChronoField.NANO_OF_SECOND),
-		SECOND(ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND),
-		MINUTE(ChronoField.MINUTE_OF_HOUR, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND),
-		HOUR(ChronoField.HOUR_OF_DAY, ChronoField.MINUTE_OF_HOUR, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND),
-		DAY_OF_MONTH(ChronoField.DAY_OF_MONTH, ChronoField.HOUR_OF_DAY, ChronoField.MINUTE_OF_HOUR, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND),
-		MONTH(ChronoField.MONTH_OF_YEAR, ChronoField.DAY_OF_MONTH, ChronoField.HOUR_OF_DAY, ChronoField.MINUTE_OF_HOUR, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND),
-		DAY_OF_WEEK(ChronoField.DAY_OF_WEEK, ChronoField.HOUR_OF_DAY, ChronoField.MINUTE_OF_HOUR, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND);
+		NANO(ChronoField.NANO_OF_SECOND, ChronoUnit.SECONDS),
+		SECOND(ChronoField.SECOND_OF_MINUTE, ChronoUnit.MINUTES, ChronoField.NANO_OF_SECOND),
+		MINUTE(ChronoField.MINUTE_OF_HOUR, ChronoUnit.HOURS, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND),
+		HOUR(ChronoField.HOUR_OF_DAY, ChronoUnit.DAYS, ChronoField.MINUTE_OF_HOUR, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND),
+		DAY_OF_MONTH(ChronoField.DAY_OF_MONTH, ChronoUnit.MONTHS, ChronoField.HOUR_OF_DAY, ChronoField.MINUTE_OF_HOUR, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND),
+		MONTH(ChronoField.MONTH_OF_YEAR, ChronoUnit.YEARS, ChronoField.DAY_OF_MONTH, ChronoField.HOUR_OF_DAY, ChronoField.MINUTE_OF_HOUR, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND),
+		DAY_OF_WEEK(ChronoField.DAY_OF_WEEK, ChronoUnit.WEEKS, ChronoField.HOUR_OF_DAY, ChronoField.MINUTE_OF_HOUR, ChronoField.SECOND_OF_MINUTE, ChronoField.NANO_OF_SECOND);
 
 
 		private final ChronoField field;
 
+		private final ChronoUnit higherOrder;
+
 		private final ChronoField[] lowerOrders;
 
 
-		Type(ChronoField field, ChronoField... lowerOrders) {
+		Type(ChronoField field, ChronoUnit higherOrder, ChronoField... lowerOrders) {
 			this.field = field;
+			this.higherOrder = higherOrder;
 			this.lowerOrders = lowerOrders;
 		}
 
@@ -266,17 +270,9 @@ public <T extends Temporal & Comparable<? super T>> T elapseUntil(T temporal, in
 		 * @return the rolled forward temporal
 		 */
 		public <T extends Temporal & Comparable<? super T>> T rollForward(T temporal) {
-			int current = get(temporal);
-			ValueRange range = temporal.range(this.field);
-			long amount = range.getMaximum() - current + 1;
-			T result = this.field.getBaseUnit().addTo(temporal, amount);
-			current = get(result);
-			range = result.range(this.field);
-			// adjust for daylight savings
-			if (current != range.getMinimum()) {
-				result = this.field.adjustInto(result, range.getMinimum());
-			}
-			return result;
+			T result = this.higherOrder.addTo(temporal, 1);
+			ValueRange range = result.range(this.field);
+			return this.field.adjustInto(result, range.getMinimum());
 		}
 
 		/**

spring-context/src/test/java/org/springframework/scheduling/support/CronExpressionTests.java

@@ -1344,6 +1344,14 @@ public void daylightSaving() {
 		actual = cronExpression.next(last);
 		assertThat(actual).isNotNull();
 		assertThat(actual).isEqualTo(expected);
+
+		cronExpression = CronExpression.parse("0 5 0 * * *");
+
+		last = ZonedDateTime.parse("2019-10-27T01:05+02:00[Europe/Amsterdam]");
+		expected = ZonedDateTime.parse("2019-10-28T00:05+01:00[Europe/Amsterdam]");
+		actual = cronExpression.next(last);
+		assertThat(actual).isNotNull();
+		assertThat(actual).isEqualTo(expected);
 	}
 
 	@Test