[Bug]: SolaceMeterConfiguration causes NullPointerException later on

[sebastiankirsch]

Bug Description

The SolaceMeterConfiguration is configured with @ConditionalOnClass(MeterRegistry.class), yet the SolaceMessageMeterBinder requires a MeterRegistry (bean) to be available. If that isn't present, consuming messages fails (see below).

java.lang.NullPointerException: Cannot invoke "io.micrometer.core.instrument.MeterRegistry.summary(io.micrometer.core.instrument.Meter$Id, io.micrometer.core.instrument.distribution.DistributionStatisticConfig, double)" because "registry" is null
	at io.micrometer.core.instrument.DistributionSummary$Builder.register(DistributionSummary.java:415)
	at io.micrometer.core.instrument.DistributionSummary$Builder.register(DistributionSummary.java:411)
	at com.solace.spring.cloud.stream.binder.meter.SolaceMessageMeterBinder.registerSizeMeter(SolaceMessageMeterBinder.java:39)
	at com.solace.spring.cloud.stream.binder.meter.SolaceMessageMeterBinder.recordMessage(SolaceMessageMeterBinder.java:26)
	at com.solace.spring.cloud.stream.binder.meter.SolaceMeterAccessor.recordMessage(SolaceMeterAccessor.java:18)
	at com.solace.spring.cloud.stream.binder.inbound.InboundXMLMessageListener.receive(InboundXMLMessageListener.java:136)
	at com.solace.spring.cloud.stream.binder.inbound.InboundXMLMessageListener.run(InboundXMLMessageListener.java:93)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:572)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
	at java.base/java.lang.Thread.run(Thread.java:1583)

Expected Behavior

SolaceMeterConfiguration should be annotated with @ConditionalOnBean(MeterRegistry.class) instead; then SolaceMeterAccessor/SolaceMessageMeterBinder either won't be defined as beans; or if a MeterRegistry exists, the aforementioned NPE won't occur.

Steps to Reproduce

In a vanilla Spring Boot project, add io.micrometer:micrometer-core as depdendency.

Solace Broker version

No response

Solace API

No response

Solace API version

No response