Fix "Nth day of week" Quartz-style cron expressions

Prior to this commit, `CronExpression` would support Quartz-style
expressions with "Nth occurence of a  dayOfWeek" semantics by using the
`TemporalAdjusters.dayOfWeekInMonth` JDK support. This method will
return the Nth occurence starting with the month of the given temporal,
but in some cases will overflow to the next or previous month.
This behavior is not expected for our cron expression support.

This commit ensures that when an overflow happens (meaning, the
resulting date is not in the same month as the input temporal), we
should instead have another attempt at finding a valid month for this
expression.

Fixes gh-34377

Author: bclozel

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -317,8 +317,16 @@ private static TemporalAdjuster lastInMonth(DayOfWeek dayOfWeek) {
 	private static TemporalAdjuster dayOfWeekInMonth(int ordinal, DayOfWeek dayOfWeek) {
 		TemporalAdjuster adjuster = TemporalAdjusters.dayOfWeekInMonth(ordinal, dayOfWeek);
 		return temporal -> {
-			Temporal result = adjuster.adjustInto(temporal);
-			return rollbackToMidnight(temporal, result);
+			// TemporalAdjusters can overflow to a different month
+			// in this case, attempt the same adjustment with the next/previous month
+			for (int i = 0; i < 12; i++) {
+				Temporal result = adjuster.adjustInto(temporal);
+				if (result.get(ChronoField.MONTH_OF_YEAR) == temporal.get(ChronoField.MONTH_OF_YEAR)) {
+					return rollbackToMidnight(temporal, result);
+				}
+				temporal = result;
+			}
+			return null;
 		};
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -39,6 +39,7 @@
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
+ * Tests for {@link CronExpression}.
  * @author Arjen Poutsma
  */
 class CronExpressionTests {
@@ -1092,6 +1093,20 @@ void quartz2ndFridayOfTheMonthDayName() {
 		assertThat(actual.getDayOfWeek()).isEqualTo(FRIDAY);
 	}
 
+	@Test
+	void quartz5thMondayOfTheMonthDayName() {
+		CronExpression expression = CronExpression.parse("0 0 0 ? * MON#5");
+
+		LocalDateTime last = LocalDateTime.of(2025, 1, 1, 0, 0, 0);
+
+		// first occurrence of 5 mondays in a month from last
+		LocalDateTime expected = LocalDateTime.of(2025, 3, 31, 0, 0, 0);
+		LocalDateTime actual = expression.next(last);
+		assertThat(actual).isNotNull();
+		assertThat(actual).isEqualTo(expected);
+		assertThat(actual.getDayOfWeek()).isEqualTo(MONDAY);
+	}
+
 	@Test
 	void quartzFifthWednesdayOfTheMonth() {
 		CronExpression expression = CronExpression.parse("0 0 0 ? * 3#5");