API

• Support W3C trace context random flag (#8012)
• Clarify that SpanBuilder.setAttribute allows null values (#8072)

Incubating

• Implement environment variable context propagation carriers (#8074)
• Deprecate ExtendedAttributes, ExtendedAttributeKey, ExtendedAttributeType, ExtendedAttributesBuilder (#8060)
• Deprecate peerServiceMapping accessor from InstrumentationConfigUtil (#8088)

SDK

Traces

• Disable warning when using TraceIdRatioBasedSampler as root sampler (#8065)
• User-supplied attributes take precedence over exception-derived attributes (#7993)
• Exclude META-INF/maven from traces SDK shaded dependencies (#8096)
• Fix inverted condition in LegacySpanProcessorInstrumentation#finishSpans (#8145)

Metrics

• Split out cumulative vs. delta storage (#8015)
• Add metrics for PeriodicMetricReader (#8038)
• Allow configuring min/max in histograms (#8095)
• Remove deprecated otel.experimental.metrics.cardinality.limit property (#8124)
• BREAKING bug fix: GlobUtil and IncludePatternMatching, used in views and declarative config matching, previously were inconsistent in case sensitivity. If a glob char (* or ?) was present, it was evaluated with case sensitivity. If no glob chars were present, it was evaluated with case insensitivity. Now, all are consistently evaluated with case sensitivity. (#8152)

Logs

• Stabilize LogRecordBuilder.setException (#8089)
• Clarify setTimestamp javadoc for event timestamp behavior (#8104)

Exporters

• OTLP: Fix marshaling for empty string attributes (#8014)
• Prometheus: Update Prometheus client to 1.5.0 (#8080)
• OTLP: Serialize exponential histogram sum as optional double (#8107)
• OTLP: Use KeyManagerFactory.getDefaultAlgorithm() in TlsUtil.keyManager() (#8122)
• OTLP: Ensure proto serializer idCache is cleared when exception is thrown (#8147)

Extensions

• Autoconfigure: Decode plus sign in resource attributes (#8059)
• Declarative config: update to 1.0 schema (#8123)
• Declarative config: add support for setting schema URL (#8028)
• Declarative config: add version mismatch warning (#8069)
• Declarative config: cache component providers in DeclarativeConfigContext (#8070)
• Declarative config: add system property substitution (#8073)
• Declarative config: add exporter customizers (#8081)
• Declarative config: add support for setting internal telemetry version (#8045)
• Deprecate View File Configuration mechanism (#8133)
• Autoconfigure: add property to allow autoconfiguration of SDK telemetry version (#8037)
• Jaeger remote sampler: refactor to leverage senders (#8046)
• Declarative config: document ObjectMapper config (#8075)
• Declarative config: Remove unchecked warning (#8090)

Project tooling

• Add architecture test to detect usage of shared internal code (#6978)
• Replace Xlint deprecation check with custom error-prone check (#8061)
• Enable error-prone's UnnecessarilyFullyQualified check (#8078)
• Small refactoring to make safety clearer (#8083)
• Rework span record benchmark and publish results (#8031)
• Add LogRecordBenchmark (#8106, #8117)

🙇 Thank you

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

@adrielp @andrzejressel @antonio-mazzini @anuraaga @arnav-dasgupta @Bhagirath00 @blakeli0 @breedx-splk @carlosalberto @dashpole @GerardoGR @jack-berg @jaydeluca @jkwatson @jmacd @laurit @lbarrios @marcingrzejszczak @MikeGoldsmith @mosesn @PeterF778 @Quaffel @ruturajjadhav07 @trask @wglad @zeitlinger