Micrometer logs java.lang.NullPointerException with Scheduled tasks

[cloudbackenddev]

Describe the bug
Logs are flooded with Micrometer null pointer errors when used with Scheduled tasks in spring boot.Refer full trace of logs under additional context section. Have given a simple example of how to replicate the issue
at java.base/java.util.Objects.requireNonNull(Objects.java:208) ~[na:na]
at io.micrometer.common.ImmutableKeyValue.(ImmutableKeyValue.java:38) ~[micrometer-commons-1.12.0.jar:1.12.0]

Environment

• Spring Boot 3.2.0
• Micrometer version [e.g. 1.12.0]
• OS: Ubuntu
• Java version: [e.g. output of java -version]
  openjdk 17.0.6 2023-01-17 LTS
  OpenJDK Runtime Environment Corretto-17.0.6.10.1 (build 17.0.6+10-LTS)
  OpenJDK 64-Bit Server VM Corretto-17.0.6.10.1 (build 17.0.6+10-LTS, mixed mode, sharing)

To Reproduce
How to reproduce the bug:
Refer this example app -> https://github.com/cloudbackenddev/demoapp

Expected behavior
No nullpointer errors are expected

Additional context
Full trace of the errot
java.lang.NullPointerException: null
at java.base/java.util.Objects.requireNonNull(Objects.java:208) ~[na:na]
at io.micrometer.common.ImmutableKeyValue.(ImmutableKeyValue.java:38) ~[micrometer-commons-1.12.0.jar:1.12.0]
at io.micrometer.common.KeyValue.of(KeyValue.java:48) ~[micrometer-commons-1.12.0.jar:1.12.0]
at io.micrometer.common.KeyValue.of(KeyValue.java:58) ~[micrometer-commons-1.12.0.jar:1.12.0]
at org.springframework.scheduling.support.DefaultScheduledTaskObservationConvention.codeNamespace(DefaultScheduledTaskObservationConvention.java:64) ~[spring-context-6.1.1.jar:6.1.1]
at org.springframework.scheduling.support.DefaultScheduledTaskObservationConvention.getLowCardinalityKeyValues(DefaultScheduledTaskObservationConvention.java:56) ~[spring-context-6.1.1.jar:6.1.1]
at org.springframework.scheduling.support.DefaultScheduledTaskObservationConvention.getLowCardinalityKeyValues(DefaultScheduledTaskObservationConvention.java:31) ~[spring-context-6.1.1.jar:6.1.1]
at io.micrometer.observation.SimpleObservation.start(SimpleObservation.java:152) ~[micrometer-observation-1.12.0.jar:1.12.0]
at io.micrometer.observation.Observation.observe(Observation.java:497) ~[micrometer-observation-1.12.0.jar:1.12.0]
at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:124) ~[spring-context-6.1.1.jar:6.1.1]
at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54) ~[spring-context-6.1.1.jar:6.1.1]
at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539) ~[na:na]
at java.base/java.util.concurrent.FutureTask.runAndReset(FutureTask.java:305) ~[na:na]
at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:305) ~[na:na]
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136) ~[na:na]
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) ~[na:na]
at java.base/java.lang.Thread.run(Thread.java:833) ~[na:na]

[marcingrzejszczak]

@bclozel I think that DefaultScheduledTaskObservationConvention in methods like this requires a null check. I'm closing this in favour of spring-projects/spring-framework#31918