SpringBoot Properties not bound properly for Spring Boot 3.x and Kotlin

Properties not bound properly for Spring Boot 3.x when using Kotlin. I thought it might be related to issue #33969.

Here is a GitHub project that reproduces the problem: https://github.com/travispeloton/spring-prop-binding-bug

With Spring Boot 3.x. You will see the following in the logs, which is NOT expected:

12:25:43.971 [main] INFO  com.example.MyComponent - management.metrics.export.statsd.host=localhost

What we expect is:

12:22:24.878 [main] INFO  com.example.MyComponent - management.metrics.export.statsd.host=127.0.0.1

Since we configured it in application.yml:

management:
  metrics:
    export:
      statsd:
        flavor: "datadog"
        # default is "localhost"
        host: "127.0.0.1"
        enabled: true

See the spring-2.x branch to see it working correctly with Spring Boot 2.x.

Comment From: travispeloton

When its working correctly, a breakpoint at the following location will be hit during startup, with the expected value:

org.springframework.boot.actuate.autoconfigure.metrics.export.statsd.StatsdProperties#setHost

I see the same problem in all Spring boot 3.x versions released thus-far.

Comment From: scottfrederick

In Spring Boot 3.0, the metrics export properties were changed, as mentioned in the migration guide. Changing management.metrics.export.statsd to management.statsd.metrics.export should fix your problem.

Comment From: travispeloton

Ok thanks. Would be nice for warnings to be printed for an obscure config change like this.

Comment From: scottfrederick

For changes in configuration properties like this, you can get warnings at startup by enabling the properties migrator, as described in the documentation.