API

• Ability to access version.properties API file with GraalVM native (#6095)

SDK

Traces

• Only call SpanProcessor onStart / onEnd if required (#6112)
• Add option to export unsampled spans from span processors (#6057)

Metrics

• Memory Mode: Adding first part support for synchronous instruments - storage (#5998)
• Base2ExponentialHistogramAggregation maxBuckets must be >= 2 (#6093)
• Convert histogram measurements to double before passing recording exemplar reservoir (#6024)

Exporters

• Add compressor SPI to support additional compression algos (#5990)
• Test OTLP exporters with different OkHttp versions (#6045)
• Refactor prometheus exporter to use io.prometheus:prometheus-metrics-exporter-httpserver, add exponential Histogram support (#6015)
• UpstreamGrpcSenderProvider uses minimal fallback managed channel when none is specified (#6110)
• OTLP exporters propagate serialization IOException instead of rethrowing as runtime (#6082)

Extensions

• Autoconfigure reads normalized otel.config.file property (#6105)

🙇 Thank you

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

@asafm @axw @fax4ever @fstab @HaloFour @jack-berg @jeanbisutti @jkwatson @lchdev @nluk @NthPortal @patrick-me @ricardo-mestre @TomasChladekSL @trask