LongTaskTimer: Failed to register Collector of type MicrometerCollector: The Collector exposes the same name multiple times

[shakuzen]

Newly released 0.12.0 is causing test failures.
https://app.circleci.com/pipelines/github/micrometer-metrics/micrometer/1801/workflows/c5177df1-1c6e-4146-a5f6-e4871c49f6bd

java.lang.IllegalArgumentException: Failed to register Collector of type MicrometerCollector: The Collector exposes the same name multiple times: my_timer_seconds
	at io.prometheus.client.CollectorRegistry.assertNoDuplicateNames(CollectorRegistry.java:71)
	at io.prometheus.client.CollectorRegistry.register(CollectorRegistry.java:51)
	at io.prometheus.client.Collector.register(Collector.java:308)
	at io.micrometer.prometheus.PrometheusMeterRegistry.lambda$applyToCollector$16(PrometheusMeterRegistry.java:479)
	at java.base/java.util.concurrent.ConcurrentHashMap.compute(ConcurrentHashMap.java:1916)
	at io.micrometer.prometheus.PrometheusMeterRegistry.applyToCollector(PrometheusMeterRegistry.java:475)
	at io.micrometer.prometheus.PrometheusMeterRegistry.newLongTaskTimer(PrometheusMeterRegistry.java:288)
	at io.micrometer.core.instrument.MeterRegistry$More.lambda$longTaskTimer$0(MeterRegistry.java:884)
	at io.micrometer.core.instrument.MeterRegistry.getOrCreateMeter(MeterRegistry.java:620)
	at io.micrometer.core.instrument.MeterRegistry.registerMeterIfNecessary(MeterRegistry.java:569)
	at io.micrometer.core.instrument.MeterRegistry.access$600(MeterRegistry.java:78)
	at io.micrometer.core.instrument.MeterRegistry$More.longTaskTimer(MeterRegistry.java:882)
	at io.micrometer.core.instrument.LongTaskTimer$Builder.register(LongTaskTimer.java:408)
	at io.micrometer.core.instrument.MeterRegistry$More.longTaskTimer(MeterRegistry.java:872)
	at io.micrometer.core.instrument.MeterRegistry$More.longTaskTimer(MeterRegistry.java:861)

[shakuzen]

This looks like a long standing issue with the implementation of the describe method for our MicrometerCollector for LongTaskTimers in the Prometheus registry. There are two MetricFamilySamples with the same name for LongTaskTimer, as opposed to the way the Timer and DistributionSummary description works: distinct MetricFamilySamples.