Version 1.22.0

API

• WARNING: GlobalOpenTelemetry trigger of autoconfiguration is now opt-in. Previously, GlobalOpenTelemetry.get triggered autoconfiguration if opentelemetry-sdk-extension-autoconfigure was detected on the classpath. That behavior is now opt-in by setting environment variable OTEL_JAVA_GLOBAL_AUTOCONFIGURE_ENABLED=true. (#5010)
• Update LoggerBuilder, MeterBuilder, TracerBuilder javadoc (#5050)

Context

• Make closing scope idempotent and non-operational when corresponding context is not current. (#5061)

SDK

• Standardize internal usage of ConfigUtil for reading environment variables and system properties (#5048)

Metrics

• Lazily initialize exponential histogram buckets (#5023)
• Delete MapCounter alternative exponential histogram implementation (#5047)
• Add toString to SdkMeter, SdkObservableInstrument, AbstractInstrumentBuilder (#5072)

Exporter

• OtlpGrpcSpanExporter, OtlpHttpSpanExporter, OtlpGrpcLogRecordExporter, OtlpHttpLogRecordExporter, ZipkinSpanExporter, and JaegerGrpcSpanExporter are now instrumented with GlobalOpenTelemetry by default. Instrumentation initializes lazily to prevent ordering issue of accessing GlobalOpenTelemetry.get before GlobalOpenTelemetry.set is called. (#4993)
• Add ConfigurableSpanExporterProvider implementation for JaegerGrpcSpanExporter (#5002)
• Add ConfigurableSpanExporterProvider, ConfigurableMetricExporterProvider, ConfigurableLogRecordExporterProvider for OtlpGrpc{Signal}Exporters and OtlpHttp{SignalExporters (#5003)
• Replace OTLP User-Agent spaces with dashes (#5080)
• Add AutoConfigurationCustomizerProvider implementation for PrometheusHttpServer (#5053)
• Add resource target_info and scope target_info metrics to PrometheusHttpServer in compliance with spec (#5039)
• Drop delta metrics in PrometheusHttpServer (#5062)
• PrometheusHttpServer drops metrics with same name and different type (#5078)

SDK Extensions

• DEPRECATION: Align autoconfigure exemplar filter names with spec. Previous names none, all, with_sampled_trace are deprecated. Use always_off, always_on, trace_based instead. (#5063)

OpenTracing Shim

• Add createTracerShim function (#4988)

🙇 Thank you

This release was possible thanks to the following contributors who shared their brilliant ideas and awesome pull requests:

@amouhadi
@brunobat
@carlosalberto
@cuichenli
@dashpole
@deejgregor
@jack-berg
@jkwatson
@lmolkova
@mateuszrzeszutek
@Oberon00
@RajatArora08
@trask
@vasireddy99
@yangtaoran

Version 1.21.0

API

API Extensions

• WARNING: opentelemetry-extension-aws has been removed following its relocation to opentelemetry-java-contrib/aws-xray-propagator, which is published under coordinates io.opentelemetry.contrib:opentelemetry-aws-xray-propagator:{version}. We will push security patches to 1.20.x as needed. The latest opentelemetry-bom will point to the latest published version, currently 1.20.1. (#4945)
• Add toString implementation to various propagator components (#4996)

SDK

Logs

• Add toString implementation to various log SDK components (#4979)

Metrics

• Add histogram collection benchmark (#4912)
• Add ExponentialHistogramIndexerBenchmark (#4989)
• Stop extra copy of exponential histogram buckets (#5020)

Exporter

• Zipkin exporter serializes EventData attributes as JSON (#4934)
• Add support for EC mTLS keys (applies to OtlpHttp{Signal}Exporter, OtlpGrpc{Signal}Exporter, JaegerGrpcSpanExporter, JaegerRemoteSampler) (#4920)
• Add Configurable{Signal}ExporterProvider implementations for Logging{Signal}Exporters (#4950)
• Add ConfigurableSpanExporterProvider implementation for ZipkinSpanExporter (#4991)
• Add Configurable{Signal}ExporterProvider implementations for OtlpJsonLogging{Signal}Exporters (#4992)
• ZipkinSpanExporter populates remoteEndpoint (#4933)

SDK Extensions

• BREAKING: Remove support for otel.experimental.sdk.enabled from autoconfigure (#4973)
• De-singleton ZPageServer implementation (#4935)
• Add auto-configure support for logging-otlp exporters (#4879)
• Move DefaultConfigProperties to internal package in opentelemetry-sdk-extension-autoconfigure-spi (#5001)

Testing

• Make APIs for asserting attributes consistent (#4882)
• Attribute assertions error messages always contain the attr key (#5027)

Semantic Conventions

• Update semantic and resource attributes for spec v0.16.0 (#4938, #5033)

OpenTracing Shim

• Handle unsupported types when setting Attributes (#4939)
• Properly set the status based on the error tag (#4962)
• Handle io.opentracing.noop.NoopSpan correctly (#4968)
• Log invalid arguments rather than throwing exceptions. (#5012)
• Stop mapping semconv values from OpenTracing to OTel. (#5016)

🙇 Thank you

This release was possible thanks to the following contributors who shared their brilliant ideas and awesome pull requests:

@ben-roling
@breedx-splk
@carlosalberto
@giraone
@jack-berg
@jkwatson
@jonatan-ivanov
@knutwannheden
@lmonkiewicz
@mateuszrzeszutek
@mattspataro
@sno544
@sriraamas
@tmccombs
@trask
@yunchen-myob

Version 1.20.1

This is a patch release on the previous 1.20.0 release, fixing the issue(s) below.

Bugfixes

• Fix bug in ComponentRegistry that produces ConcurrentModificationException when reading metrics at the same time as obtaining a meter. (#4951)

Version 1.20.0

API

• Fix bug in W3CBaggagePropagator that caused + characters to be decoded as whitespace . (#4898)

API Extensions

• DEPRECATION: the opentelemetry-extension-aws module containing various AwsXrayPropagator implementations has been deprecated for removal in next major version. A copy of the code will instead be maintained in opentelemetry-java-contrib/aws-xray-propagator and published under coordinates io.opentelemetry.contrib:opentelemetry-aws-xray-propagator:{version}. (#4862)

SDK

Traces

• Add graal hints for shaded dependencies, allowing JcTools queue to be used in graal environment. (#4832)
• Sampler#getDescription() implementations are now locale independent. (#4877)
• Allow SDK to run in environments prohibiting use of sun.misc.Unsafe. (#4902)

Metrics

• Add toString to AbstractInstrument. (#4833)
• Add zero bucket boundary to default explicit bucket histogram aggregation. (#4819)

Logs

• Optimize log hot path, reducing allocations significantly. (#4913)
• BREAKING: Add Context argument to LogRecordProcessor#onEmit. (#4889)

Exporter

• OtlpLogging{Signal}Exporters encode enums as numbers. (#4783)
• Add User-Agent header of OTel OTLP Exporter Java/{version} to OTLP export requests. (#4784)

SDK Extensions

• WARNING: opentelemetry-sdk-extension-aws has been removed following its relocation to opentelemetry-java-contrib/instrumentation-aws-xray, which is published under coordinates io.opentelemetry.contrib:opentelemetry-aws-resources:{version}. We will push security patches to 1.19.x as needed. The latest opentelemetry-bom will point to the latest published version, currently 1.19.0. (#4830)
• WARNING: opentelemetry-sdk-extension-resources has been removed following its relocation to opentelemetry-java-instrumentation/instrumentation/resources/library, which is published under coordinates io.opentelemetry.instrumentation:opentelemetry-resources:{version}. We will push security patches to 1.19.x as needed. The latest opentelemetry-bom will point to the latest published version, currently 1.19.0. (#4828)
• Add autoconfigure support for BatchLogRecordProcessor. (#4811)
• Autoconfigure performs percent decoding on otel.resource.attributes values. (#4653)
• Unify compression configuration for exporters including (#4775): * Fix handling of none in OTLP exporters. * Add JaegerGrpcSpanExporterBuilder#setCompression(String). * Add ZipkinSpanExporterBuilder#setCompression(String).

Semantic Conventions

• Add migration notes to deprecated attributes (#4840)

OpenTracing Shim

• Use opentracing-shim as instrumentation scope name. (#4890)
• Add full support for multiple parents. (#4916)

🙇 Thank you

This release was possible thanks to the following contributors who shared their brilliant ideas and awesome pull requests:

@amouhadi
@bogdandrutu
@breedx-splk
@carlosalberto
@codeboten
@Donnerbart
@fniephaus
@jack-berg
@jkwatson
@jsuereth
@kubawach
@lgfa29
@lmonkiewicz
@lukiano
@marcingrzejszczak
@mateuszrzeszutek
@mkorzeniewski
@reyang
@rrva
@sdeleuze
@trask

Version 1.19.0

This release contains a large number of changes to the log signal following a series of significant changes to the log specification. The changes include renaming key classes like LogExporter to LogRecordExporter, and LogProcessor to LogRecordProcessor, and LogEmitter to Logger, and more. Additionally, a log API component has been added for emitting events and for writing log appenders. Note, the log API is not a substitute for traditional log frameworks like Log4j, JUL, SLF4J, or Logback. While the event portion of the API is intended for instrumentation authors and end users, the API for emitting LogRecords is not. See LoggerProvider and Logger javadoc for more details.

General

• Add opentelemetry-bom as a dependency to opentelemetry-bom-alpha, ensuring synchronization between alpha and stable artifact versions.

API

API Extensions

• WARNING: opentelemetry-extension-annotations has been removed following its relocation to opentelemetry-java-instrumentation/instrumentation-annotations, which is published under coordinates io.opentelemetry.instrumentation:opentelemetry-instrumentation-annotations:{version}. We will push security patches to 1.18.x as needed. The latest opentelemetry-bom will point to the latest published version, currently 1.18.0.

Logs

• Introduce log API for emitting events and writing log appenders. The artifact is available at coordinates io.opentelemetry:opentelemetry-api-logs:1.19.0-alpha.

SDK

Metrics

• Change exponential histogram bucket boundaries to be lower exclusive / upper inclusive, instead of lower inclusive / upper exclusive.

Logs

• BREAKING: Rename SdkLogEmitterProvider to SdkLoggerProvider. OpenTelemetrySdkBuilder#setLogEmitterProvider has changed to OpenTelemetrySdkBuilder#setLoggerProvider. OpenTelemetrySdk#getSdkLogEmitterProvider has changed to OpenTelemetrySdk#getSdkLoggerProvider. AutoConfigurationCustomizer#addLogEmitterProviderCustomizer has changed to AutoConfigurationCustomizer#addLoggerProviderCustomizer.
• BREAKING: Rename LogEmitter to Logger.
• BREAKING: Rename LogExporter to LogRecordExporter. SystemOutLogExporter has changed to SystemOutLogRecordExporter. OtlpJsonLoggingLogExporter has changed to OtlpJsonLoggingLogRecordExporter. OtlpHttpLogExporter has changed to OtlpHttpLogRecordExporter. OtlpGrpcLogExporter has changed to OtlpGrpcLogRecordExporter. InMemoryLogExporter has changed to InMemoryLogRecordExporter. ConfigurableLogExporterProviderhas changed toConfigurableLogRecordExporterProvider`.
• BREAKING: Rename LogData to LogRecordData. TestLogData has changed to TestLogRecordData.
• BREAKING: Rename LogProcessor to LogRecordProcessor. BatchLogProcessor has changed to BatchLogRecordProcessor. SimpleLogProcessor has changed to SimpleLogRecordProcessor.

Exporter

• OTLP log record exporters now include dropped_attributes_count.

SDK Extensions

• Autoconfigure now supports an option to disable the SDK. If otel.sdk.disabled=true, AutoConfiguredOpenTelemetrySdk#getOpenTelemetrySdk() returns a minimal (but not noop) OpenTelemetrySdk with noop tracing, metric and logging providers. The same minimal instance is set to GlobalOpenTelemetry. The now deprecated property otel.experimental.sdk.enabled will continue to work in the same way during a transition period.
• Fix ProcessResource directory separator to use / or \ instead of : or ;.
• DEPRECATION: the opentelemetry-sdk-extension-resource module containing various ResourceProvider implementations has been deprecated for removal in next major version. A copy of the code will instead be maintained in opentelemetry-java-instrumentation/instrumentation/resources/library and published under coordinates io.opentelemetry.instrumentation:opentelemetry-resources:{version}.
• DEPRECATION: the opentelemetry-sdk-extension-aws module containing AWS ResourceProvider implementations has been deprecated for removal in next major version. A copy of the code will instead be maintained in opentelemetry-java-contrib/aws-resources and published under coordinates io.opentelemetry.contrib:opentelemetry-aws-resources:{version}.

OpenTracing Shim

• Fully support Baggage-only propagation.

Semantic conventions

• The semantic conventions have been updated to 1.13.0.

🙇 Thank you

This release was possible thanks to the following contributors who shared their brilliant ideas and awesome pull requests:

@anuraaga
@breedx-splk
@brunobat
@carlosalberto
@jack-berg
@jamesmoessis
@jkwatson
@jmacd
@joshua-bell-sonrai
@jsuereth
@mateuszrzeszutek
@rapphil
@SampathKumarAmex
@trask

Version 1.18.0

SDK

• Added scope attributes to InstrumentationScopeInfo accessible via InstrumentationScopeInfo#getAttributes(). Will add the ability to specify scope attributes in Meter, Tracer, and Logger in a future version.
• DEPRECATION: The InstrumentationScopeInfo#create(String, String, String) method has been deprecated in favor of InstrumentationScopeInfo#builer(String).setVersion(String).setSchemaUrl(String).build().
• Optimize Resource#merge(Resource) by returning early if the other resource is empty.

Logs

• Fix module name of opentelemetry-sdk-logs by changing from io.opentelemetry.sdk.extension.logging to io.opentelemetry.sdk.logs.

Testing

• Add methods to assert attributes do not contain keys via AttributeAssert#doesNotContainKey().

Exporter

• Added ability to specify local IP address in ZipkinSpanExporter via ZipkinSpanExporterBuilder#setLocalIpAddressSupplier(Supplier<InetAddress>).
• Upgrade to OTLP protobuf version 0.19.0.
• OTLP exporters now serialize InstrumentationScopeInfo#getAttributes().
• Stop publishing opentelemetry-exporter-jaeger-proto. The opentelemetry-bom will include a constraint on the last published version 1.17.0. If security issues are discovered, patches will be published to 1.17.x.

SDK Extensions

• BREAKING: opentelemetry-sdk-extension-metric-incubator, opentelemetry-sdk-extension-tracing-incubator, and opentelemetry-sdk-extension-zpages merged into opentelemetry-sdk-extension-incubator.
• BREAKING: Move opentelemetry-sdk-extension-jfr-events to opentelemetry-java-contrib/jfr-events. It will now be published under the coordinates io.opentelemetry.contrib:opentelemetry-jfr-events:{version}.
• BREAKING: Move opentelemetry-extension-noop-api to opentelemetry-java-contrib/noop-api. It will now be published under the coordinates io.opentelemetry.contrib:opentelemetry-noop-api:{version}.
• Improve ECS resource detection to include aws.ecs.container.arn, container.image.name, container.image.tag, aws.ecs.container.image.id, aws.log.group.arns, aws.log.group.names, aws.log.steam.names, aws.ecs.task.arn, aws.ecs.task.family, and aws.ecs.task.revision.
• Fix resource container.id detection when using k8s with containerd v1.5.0+.
• Add experimental ConditionalResourceProvider SPI, for conditionally applying resource providers based on current config and resource.

Micrometer shim

• BREAKING: Move opentelemetry-micrometer1-shim to opentelemetry-java-instrumentation/instrumentation/micrometer/micrometer-1.5/library. It will now be published under the coordinates io.opentelemetry.instrumentation:opentelemetry-micrometer-1.5:{version}.

🙇 Thank you

This release was possible thanks to the following contributors who shared their brilliant ideas and awesome pull requests:

@anuraaga
@bogdandrutu
@breedx-splk
@felixscheinost
@jack-berg
@jj22ee
@jkwatson
@kubawach
@mateuszrzeszutek
@mmanciop
@SampathKumarAmex
@trask
@willarmiros
@wzy531a

Version 1.17.0

API

API Extensions

• DEPRECATION: the opentelemetry-extension-annotations module containing @WithSpan and @SpanAttribute annotations has been deprecated for removal in next major version. A copy of the code will instead be maintained in opentelemetry-java-instrumentation/instrumentation-annotations and published under coordinates io.opentelemetry.instrumentation:opentelemetry-instrumentation-annotations:{version}.

SDK

Traces

• Add default implementation for SpanData#getInstrumentationScopeInfo() and ReadableSpan#getInstrumentationScopeInfo(). This fixes a previous mistake where those interfaces were extended without default implementation, a breaking change for source compatibility. Stricter checks have been added to ensure this mistake is not repeated.

Logs

• BREAKING: delete LogDataBuilder. A similar implementation of LogData called TestLogData has been added to opentelemetry-sdk-logs-testing.
• BREAKING: rename LogProcessor#emit(LogData) to LogProcessor#onEmit(ReadWriteLogRecord). The argument change from LogData to ReadWriteLogRecord allows implementations to mutate logs. To obtain LogData, call ReadWriteLogRecord#toLogData().
• Optimize SdkLogEmitterProvider to return noop LogEmitter when no LogProcessors are registered.

Exporter

• Split out shared and internal exporter classes from opentelemetry-exporter-otlp-common to opentelemetry-exporter-common.
• Add experimental support for OTLP header based authentication. To use, add a dependency on opentelemetry-exporter-common and call io.opentelemetry.exporter.internal.auth.Authenticator#setAuthenticatorOnDelegate(OtlpHttp{Signal}Builder, Authenticator).
• Add ability to collect export metrics on ZipkinSpanExporter via ZipkinSpanExporter#setMeterProvider(MeterProvider).
• Minor optimization to OkHttp based exporters to cache endpoint URLs. Applies to OtlpHttp{Signal}Exporter, OtlpGrpc{Signal}Exporter, and more.
• Fix diagnostic log message in OtlpGrpc{Signal}Exporter to include correct environment variables.

SDK Extensions

• Extend View file based configuration with support for specifying explicit bucket histogram bucket boundaries and exponential bucket counts.
• Extend autoconfigure SPI AutoConfigurationCustomizerProvider and ResourceProvider with option to specify ordering.
• Add autoconfigure SPI with ConfigurableLogExporterProvider, allowing custom named log exporters to be provided and selected via autoconfigure.
• Extend autoconfigure SPI with AutoConfigurationCustomizer#addPropertiesCustomizer, providing the ability examine current configuration properties and add / overwrite properties.

🙇 Thank you

This release was possible thanks to the following contributors who shared their brilliant ideas and awesome pull requests:

@anuraaga
@bogdandrutu
@breedx-splk
@chalin
@DaveCTurner
@deejgregor
@Donnerbart
@GrahamLea
@iRevive
@jack-berg
@JavaPerformance
@jkwatson
@lmolkova
@mateuszrzeszutek
@sfriberg
@trask
@trivikr

Version 1.16.0

API

• Fix bug ImmutableKeyValuePairs implementation that causes ArrayIndexOutOfBoundsException to be thrown under certain conditions.

SDK

Traces

• Optimize BatchSpanProcessor using JcTools.

Metrics

• Tighten up exponential histogram implementation for alignment with specification: Default to 160 positive and negative buckets. Remove ability to configure starting scale. Minimum number of buckets is one instead of zero.
• Allow MetricExporter and MetricReader to influence default aggregation. The default aggregation is used when no registered views match an instrument.

Exporter

• Fix handling of client keys in PEM format.
• For OTLP exporters, change behavior to use OkHttpGrpcExporter (OkHttp implementation that doesn't use any gRPC dependencies) unless OtlpGrpc{Signal}Builder#setChannel(ManagedChannel) is called by user. Previously, OkHttpGrpcExporter was used if no gRPC implementation was found on classpath.
• Add support to configure default aggregation on OTLP metric exporters via Otlp{Protocol}MetricExporterBuilder#setDefaultAggregationSelector(DefaultAggregationSelector).

Testing

• Add span status assertions.

SDK Extensions

• Autoconfigure properly handles non-string system properties.
• Autoconfigure normalizes hyphens - to periods . when accessing ConfigProperties.

OpenTracing Shim

• Add support for span wrappers.
• Store OpenTracing SpanContext in OpenTracing Span wrapper.
• Use Baggage of active span.

🙇 Thank you

This release was possible thanks to the following contributors who shared their brilliant ideas and awesome pull requests:

@aaron-ai
@anuraaga
@breedx-splk
@carlosalberto
@codeboten
@cuichenli
@fax4ever
@HaloFour
@jack-berg
@jkwatson
@jsuereth
@mateuszrzeszutek
@mohitmahi
@pavolloffay
@pureklkl
@trask
@xiangtianyu
@zeitlinger

Version 1.15.0

API

• Add batch callback API, allowing a single callback to record measurements to multiple metric instruments.

SDK

Metrics

• SdkMeterProvider#toString() now returns a useful string describing configuration.
• Fix bug preventing proper function of Metrics SDK when multiple readers are present (#4436).
• Fix reporting intervals for metrics for delta readers (#4400).

Exporter

• BREAKING: merge all stable OTLP exporters into opentelemetry-exporter-otlp. opentelemetry-exporter-otlp-trace, opentelemetry-exporter-otlp-metrics, opentelemetry-exporter-otlp-http-trace, and opentelemetry-exporter-otlp-http-metrics are no longer published and their contents have been merged into a single artifact.
• BREAKING: merge log OTLP exporters into opentelemetry-exporter-otlp-logs. opentelemetry-exporter-otlp-http-logs is no longer published and its contents have been merged into a single artifact.
• Upgrade to OTLP protobuf version 0.18.0.
• RetryInterceptor retries on SocketTimeoutException with no message.
• Added JaegerGrpcSpanExporterBuilder#setMeterProvider(), enabling support of experimental jaeger span export metrics.
• DEPRECATION: the opentelemetry-exporter-jaeger-proto module containing jaeger proto definitions and corresponding generated classes is deprecated for removal in next major version.
• OTLP gRPC exporters support overriding :authority via OtlpGrpc*ExporterBuilder#addHeader("host", "my-authority-override").

SDK Extensions

• BREAKING: Move ConfigureableMetricExporterProvider from opentelemetry-sdk-extension-autoconfigure to stable opentelemetry-sdk-extension-autoconfigure-spi.
• Autoconfigure now supports multiple values for otel.metrics.exporter.
• Autoconfigure now supports general attribute limits, applicable to span attributes, span event attributes, span link attributes, and log attributes.
• Autoconfigure now supports an experimental option to disable the SDK. If otel.experimental.sdk.enabled=true, AutoConfiguredOpenTelemetrySdk#getOpenTelemetrySdk() returns a minimal (but not noop) OpenTelemetrySdk. The same minimal instance is set to GlobalOpenTelemetry.
• New "get or default" methods have been added to ConfigProperties. E.g. ConfigProperties#getString("otel.metrics.exporter", "otlp") fetches the value for the property otel.metrics.exporter and returns otlp if it is not set.
• Fix bug in ContainerResource provider that caused it to throw an exception in some instances when containerd is used.

Micrometer shim

• Cache descriptions such that metrics with the same name use the first seen description.

🙇 Thank you

This release was possible thanks to the following contributors who shared their brilliant ideas and awesome pull requests:

@anuraaga
@breedx-splk
@chenjazz
@cyrille-leclerc
@donce
@Donnerbart
@evantorrie
@jack-berg
@jkwatson
@jonahaapala
@jsuereth
@kubawach
@laurit
@marcalff
@mateuszrzeszutek
@nicklocaso
@Oberon00
@pkgonan
@rupinder10
@trask
@wallezhang

Version v1.14.0

The metrics SDK is stable! New stable artifacts include:

• io.opentelemetry:opentelemetry-sdk-metrics (also now included in io.opentelemetry:opentelemetry-sdk)
• io.opentelemetry:opentelemetry-exporter-otlp-metrics (also now included in io.opentelemetry:opentelemetry-exporter-otlp)
• io.opentelemetry:opentelemetry-exporter-otlp-http-metrics
• Metrics testing components have been moved from io.opentelemetry:opentelemetry-sdk-metrics-testing to the stable io.opentelemetry:opentelemetry-sdk-testing.

While the API of the metrics SDK is now stable, there are a couple of known issues that will be addressed in the next release:

• The start time is incorrect for delta metrics when the first recording for a set of attributes occurs after the first collections (#4400).
• Registering multiple readers results in incorrect metrics (#4436).

SDK

Traces

• Fix bug where non-runtime exception breaks BatchSpanProcessor.
• Fix bug preventing attribute limits from applying to exception events.

Logs

• BREAKING: Drop deprecated methods referencing InstrumentationLibraryInfo from Log SDK.

Metrics

• Instrument name is validated. If invalid, a warning is logged and a noop instrument is returned.
• Default unit is empty instead of 1. If an invalid unit is set, a warning is logged and empty is used.
• Ensure symmetry between type of PointData and their type of exemplars (double or long).
• BREAKING: Rename MetricReader#flush() to MetricReader#forceFlush().
• Introduce AggregationTemporalitySelector interface for selecting aggregation temporality based on instrument. MetricReader and MetricExporter extend AggregationTemporalitySelector.

SDK Extensions

• BREAKING: Remove deprecated option to specify temporality with otel.exporter.otlp.metrics.temporality. Use otel.exporter.otlp.metrics.temporality.preference instead.
• Log warning when AwsXrayPropagator can't identify parent span id.
• Fix jaeger remote sampling bug preventing correct parsing of 0-probability sampling strategies.

Exporter

• Fix prometheus exporter formatting bug when there are no attributes.
• Ensure prometheus metrics with the same name are serialized as a group.
• BREAKING: OtlpHttpMetricExporterBuilder and OtlpGrpcMetricExporterBuilder configure aggregation temporality via #setAggregationTemporalitySelector(AggregationTemporalitySelector).

Testing

• BREAKING: Metrics testing components added to stable io.opentelemetry:opentelemetry-sdk-testing module, including InMemoryMetricReader, InMemoryMetricExporter, and MetricAssertions.assertThat(MetricData) has been moved to OpenTelemetryAssertions.assertThat(MetricData).
• BREAKING: The patterns for metrics assertions have been adjusted to better align with assertj conventions. See #4444 for examples demonstrating the change in assertion patterns.
• BREAKING: Metric assertion class names have been simplified.
• Add TraceAssert.hasSpansSatisfyingExactlyInAnyOrder(..) methods.

Micrometer shim

• Instrumentation scope name changed to io.opentelemetry.micrometer1shim.

Project tooling

• Many improvements to the build and release workflows. Big thanks to @trask for driving standardization across opentelemetry-java, opentelemetry-java-instrumentation, and opentelemetry-java-contrib!

🙇 Thank you

This release was possible thanks to the following contributors who shared their brilliant ideas and awesome pull requests:

@anuraaga
@arminru
@cbos
@chrismgrayftsinc
@gfelbing
@jack-berg
@jkwatson
@jsuereth
@kubawach
@laurit
@mateuszrzeszutek
@middlewareman
@OliverO2
@trask
@wallezhang
@ZQiannnn