histogram without distribution of values transmits bucket_counts but not explicit_bounds using the micrometer timer

Describe the bug

I noticed that the histogram which is generated by the micrometer 1.5 instrumentation does not match the specification. The HistogramDataPoint contains the field count, sum and bucket_counts(with array length 1) but no explicit_bounds (see log below):

{\"name\":\"test.timer\",\"description\":\"description\",\"unit\":\"s\",\"histogram\":{\"dataPoints\":[{\"startTimeUnixNano\":\"1743493817029495356\",\"timeUnixNano\":\"1743493877039760941\",\"count\":\"60\",\"sum\":8.737000000000002,\"bucketCounts\":[\"60\"],\"min\":0.019,\"max\":0.293}],\"aggregationTemporality\":2}}

I found following comment in the specification which says that an HistogramDataPointneeds to have booth explicit_bounds and bucket_counts set with both length or booth omitted: https://github.com/open-telemetry/opentelemetry-proto/blob/v0.9.0/opentelemetry/proto/metrics/v1/metrics.proto#L496

I am not sure if this is related to the OpenTelemetryMeterRegistry or faulty for all histogram metrics. I discovered the issue while receiving the histogram metric on the otlp input of the elastic apm server: https://github.com/elastic/apm-data/blob/main/input/otlp/metrics.go#L367

Steps to reproduce

1. instantiate io.micrometer.core.instrument.Timer
2. set OTEL_INSTRUMENTATION_MICROMETER_ENABLED=true
3. observe outgoing data via OTEL_METRICS_EXPORTER=console

[java-app-otel] | [otel.javaagent 2025-04-01 13:34:56:783 +0000] [PeriodicMetricReader-1] INFO io.opentelemetry.exporter.logging.LoggingMetricExporter - metric: ImmutableMetricData{resource=Resource{schemaUrl=https://opentelemetry.io/schemas/1.24.0, attributes={container.id="a77637a48f8cf2b64630dbb2489a5a74093d5195953a77d8c8411662ccbb56c6", deployment.environment="qa", host.arch="aarch64", host.name="a77637a48f8c", os.description="Linux 6.12.7-200.fc41.aarch64", os.type="linux", process.command_args=[/opt/java/openjdk/bin/java, -javaagent:/app/elastic-otel-javaagent.jar, -Dotel.instrumentation.logback-appender.experimental.capture-marker-attribute=true, -jar, /app/app.jar], process.executable.path="/opt/java/openjdk/bin/java", process.pid=1, process.runtime.description="Eclipse Adoptium OpenJDK 64-Bit Server VM 17.0.14+7", process.runtime.name="OpenJDK Runtime Environment", process.runtime.version="17.0.14+7", service.instance.id="a93f4706-44e2-4fb3-b33b-c4fe204b0345", service.name="java-demo-app-otel", telemetry.distro.name="elastic", telemetry.distro.version="1.3.0", telemetry.sdk.language="java", telemetry.sdk.name="opentelemetry", telemetry.sdk.version="1.47.0"}}, instrumentationScopeInfo=InstrumentationScopeInfo{name=io.opentelemetry.micrometer-1.5, version=null, schemaUrl=null, attributes={}}, name=test.timer, description=description, unit=s, type=HISTOGRAM, data=ImmutableHistogramData{aggregationTemporality=CUMULATIVE, points=[ImmutableHistogramPointData{getStartEpochNanos=1743514436723244038, getEpochNanos=1743514496732826544, getAttributes={}, getSum=7.910000000000002, getCount=60, hasMin=true, getMin=0.0, hasMax=true, getMax=0.294, getBoundaries=[], getCounts=[60], getExemplars=[]}]}}

Expected behavior

https://github.com/open-telemetry/opentelemetry-proto/blob/v0.9.0/opentelemetry/proto/metrics/v1/metrics.proto#L498

Actual behavior

See description above

Javaagent or library instrumentation version

opentelemetry-micrometer-1.5

Environment

JDK: eclipse-temurin:17-jre
OS: alpine

Additional context

No response

Start by inspecting the io.opentelemetry.micrometer-1.5 integration, especially OpenTelemetryMeterRegistry, and reproduce the issue with a Micrometer Timer and the console exporter. Confirm the emitted HistogramDataPoint against the referenced specification; done means bucket_counts and explicit_bounds are represented consistently for a histogram without a value distribution.