Revise StopWatch for flexible time units in nanosecond precision

Closes gh-25803

spring-core/src/test/java/org/springframework/util/StopWatchTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -47,7 +47,7 @@ class StopWatchTests {
 
 	@Test
 	void failureToStartBeforeGettingTimings() {
-		assertThatIllegalStateException().isThrownBy(stopWatch::getLastTaskTimeMillis);
+		assertThatIllegalStateException().isThrownBy(stopWatch::getLastTaskInfo);
 	}
 
 	@Test