Preserve milliseconds in build info timestamp

See gh-43612

Author: gavarava

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/MavenBuildOutputTimestamp.java

@@ -88,7 +88,7 @@ Instant toInstant() {
 		try {
 			Instant instant = OffsetDateTime.parse(this.timestamp)
 				.withOffsetSameInstant(ZoneOffset.UTC)
-				.truncatedTo(ChronoUnit.SECONDS)
+				.truncatedTo(ChronoUnit.MILLIS)
 				.toInstant();
 			if (instant.isBefore(DATE_MIN) || instant.isAfter(DATE_MAX)) {
 				throw new IllegalArgumentException(

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/test/java/org/springframework/boot/maven/MavenBuildOutputTimestampTests.java

@@ -52,8 +52,13 @@ void shouldParseIso8601() {
 	}
 
 	@Test
-	void shouldParseIso8601WithMilliseconds() {
-		assertThat(parse("2011-12-03T10:15:30.12345Z")).isEqualTo(Instant.parse("2011-12-03T10:15:30Z"));
+	void shouldParseIso8601WithSeconds_whenMillisecondsNotPresent() {
+		assertThat(parse("2011-12-03T10:15:30Z")).isEqualTo(Instant.parse("2011-12-03T10:15:30Z"));
+	}
+
+	@Test
+	void shouldParseIso8601WithMillisecondsPreserved_whenPresent() {
+		assertThat(parse("2024-12-19T19:59:39.040Z")).isEqualTo(Instant.parse("2024-12-19T19:59:39.040Z"));
 	}
 
 	@Test