Avoid NPE when a PeriodicTrigger has no initial delay

Closes gh-36081

Author: wilkinsona

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/scheduling/ScheduledTasksEndpoint.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.actuate.scheduling;
 
 import java.lang.reflect.Method;
+import java.time.Duration;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.LinkedHashMap;
@@ -186,7 +187,8 @@ protected IntervalTaskDescriptor(TaskType type, IntervalTask task) {
 
 		protected IntervalTaskDescriptor(TaskType type, TriggerTask task, PeriodicTrigger trigger) {
 			super(type, task.getRunnable());
-			this.initialDelay = trigger.getInitialDelayDuration().toMillis();
+			Duration initialDelayDuration = trigger.getInitialDelayDuration();
+			this.initialDelay = (initialDelayDuration != null) ? initialDelayDuration.toMillis() : 0;
 			this.interval = trigger.getPeriodDuration().toMillis();
 		}
 

spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/scheduling/ScheduledTasksEndpointTests.java

@@ -113,6 +113,20 @@ void fixedDelayTriggerIsReported() {
 		});
 	}
 
+	@Test
+	void noInitialDelayFixedDelayTriggerIsReported() {
+		run(NoInitialDelayFixedDelayTriggerTask.class, (tasks) -> {
+			assertThat(tasks.getCron()).isEmpty();
+			assertThat(tasks.getFixedRate()).isEmpty();
+			assertThat(tasks.getCustom()).isEmpty();
+			assertThat(tasks.getFixedDelay()).hasSize(1);
+			FixedDelayTaskDescriptor description = (FixedDelayTaskDescriptor) tasks.getFixedDelay().get(0);
+			assertThat(description.getInitialDelay()).isEqualTo(0);
+			assertThat(description.getInterval()).isEqualTo(1000);
+			assertThat(description.getRunnable().getTarget()).isEqualTo(FixedDelayTriggerRunnable.class.getName());
+		});
+	}
+
 	@Test
 	void fixedRateScheduledMethodIsReported() {
 		run(FixedRateScheduledMethod.class, (tasks) -> {
@@ -142,6 +156,20 @@ void fixedRateTriggerIsReported() {
 		});
 	}
 
+	@Test
+	void noInitialDelayFixedRateTriggerIsReported() {
+		run(NoInitialDelayFixedRateTriggerTask.class, (tasks) -> {
+			assertThat(tasks.getCron()).isEmpty();
+			assertThat(tasks.getFixedDelay()).isEmpty();
+			assertThat(tasks.getCustom()).isEmpty();
+			assertThat(tasks.getFixedRate()).hasSize(1);
+			FixedRateTaskDescriptor description = (FixedRateTaskDescriptor) tasks.getFixedRate().get(0);
+			assertThat(description.getInitialDelay()).isEqualTo(0);
+			assertThat(description.getInterval()).isEqualTo(2000);
+			assertThat(description.getRunnable().getTarget()).isEqualTo(FixedRateTriggerRunnable.class.getName());
+		});
+	}
+
 	@Test
 	void taskWithCustomTriggerIsReported() {
 		run(CustomTriggerTask.class, (tasks) -> {
@@ -223,6 +251,16 @@ public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
 
 	}
 
+	static class NoInitialDelayFixedDelayTriggerTask implements SchedulingConfigurer {
+
+		@Override
+		public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
+			PeriodicTrigger trigger = new PeriodicTrigger(Duration.ofSeconds(1));
+			taskRegistrar.addTriggerTask(new FixedDelayTriggerRunnable(), trigger);
+		}
+
+	}
+
 	static class FixedRateTriggerTask implements SchedulingConfigurer {
 
 		@Override
@@ -235,6 +273,17 @@ public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
 
 	}
 
+	static class NoInitialDelayFixedRateTriggerTask implements SchedulingConfigurer {
+
+		@Override
+		public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
+			PeriodicTrigger trigger = new PeriodicTrigger(Duration.ofSeconds(2));
+			trigger.setFixedRate(true);
+			taskRegistrar.addTriggerTask(new FixedRateTriggerRunnable(), trigger);
+		}
+
+	}
+
 	static class CronTriggerTask implements SchedulingConfigurer {
 
 		@Override