Polish "Preserve milliseconds in build info timestamp"

See gh-43612

Author: snicoll

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

@@ -21,7 +21,6 @@
 import java.time.OffsetDateTime;
 import java.time.ZoneOffset;
 import java.time.format.DateTimeParseException;
-import java.time.temporal.ChronoUnit;
 
 import org.springframework.util.StringUtils;
 
@@ -86,10 +85,7 @@ Instant toInstant() {
 			return null;
 		}
 		try {
-			Instant instant = OffsetDateTime.parse(this.timestamp)
-				.withOffsetSameInstant(ZoneOffset.UTC)
-				.truncatedTo(ChronoUnit.MILLIS)
-				.toInstant();
+			Instant instant = OffsetDateTime.parse(this.timestamp).withOffsetSameInstant(ZoneOffset.UTC).toInstant();
 			if (instant.isBefore(DATE_MIN) || instant.isAfter(DATE_MAX)) {
 				throw new IllegalArgumentException(
 						String.format("'%s' is not within the valid range %s to %s", instant, DATE_MIN, DATE_MAX));

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 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.
@@ -48,17 +48,17 @@ void shouldNotParseSingleCharacter() {
 
 	@Test
 	void shouldParseIso8601() {
-		assertThat(parse("2011-12-03T10:15:30Z")).isEqualTo(Instant.parse("2011-12-03T10:15:30Z"));
+		assertThat(parse("2011-12-03T10:15:30Z")).isEqualTo(Instant.parse("2011-12-03T10:15:30.000Z"));
 	}
 
 	@Test
-	void shouldParseIso8601WithSeconds_whenMillisecondsNotPresent() {
-		assertThat(parse("2011-12-03T10:15:30Z")).isEqualTo(Instant.parse("2011-12-03T10:15:30Z"));
+	void shouldParseIso8601WithMilliseconds() {
+		assertThat(parse("2011-12-03T10:15:30.123Z")).isEqualTo(Instant.parse("2011-12-03T10:15:30.123Z"));
 	}
 
 	@Test
-	void shouldParseIso8601WithMillisecondsPreserved_whenPresent() {
-		assertThat(parse("2024-12-19T19:59:39.040Z")).isEqualTo(Instant.parse("2024-12-19T19:59:39.040Z"));
+	void shouldParseIso8601WithSeconds() {
+		assertThat(parse("2011-12-03T10:15:30Z")).isEqualTo(Instant.parse("2011-12-03T10:15:30.000Z"));
 	}
 
 	@Test