SmallRye Metrics - @Gauge methods analyzed in MetricsInterceptor should be registered for reflection

[mkouba]

Describe the bug
MetricsInterceptor does not see the methods annotated with @Gauge if they're not registered for reflection by another extension or annotated with @RegisterForReflection.

Expected behavior
Methods are registered automatically.

Actual behavior
Methods are not registered automatically. MetricsInterceptor does not register a gauge method. No error or warning message.

To Reproduce
Steps to reproduce the behavior:

1. Add the following bean class to the microprofile-metrics-quickstart
2. Build the native image
3. Run the image - you should see the STARTUP message in the log but the gauge is not listed on http://localhost:8080/metrics/application

@ApplicationScoped
public class DummyGauge {

    void init(@Observes StartupEvent event) {
       System.out.println("STARTUP!");
    }

    @Gauge(name = "dummyGauge", unit = MetricUnits.NONE)
    public Long dummyGauge() {
        return 42l;
    }
}

Workaround
Annotated the class with @RegisterForReflection.

[geoand]

Will this also be solved by #6989?

[mkouba]

Nope, that's a different issue. This registration must be perfomed in the SM Metrics extension.