What micrometer-metrics/micrometer shipped

This week: HdrHistogram types removed from the TimeWindowPercentileHistogram signature hierarchy, Dependabot relabeling fixed for Gradle upgrades and branch-based configs, and build images bumped for JDK 25, 21 and 17.

This week in Micrometer: TimeWindowPercentileHistogram no longer exposes HdrHistogram types in its supertype hierarchy, which matters because HdrHistogram is only an implementation dependency of micrometer-core. The Dependabot relabel workflow was also corrected to identify root Gradle dependency upgrades when a target branch is set, and it now passes repository context to gh without a checkout. Transitive dependency upgrades get their own labels for cleaner release notes, and the cimg/openjdk build images were upgraded across JDK 25, 21 and 17.

Micrometer 1.18.0-RC1 is out, alongside 1.17.2 and 1.16.8 with fixes for Basic auth password whitespace, getProcessCpuTime reflection, JMS proxy return types and CaffeineCacheMetrics Kotlin interop. Atlas FunctionTimer statistics now publish as rates.

Micrometer 1.18.0-RC1 is available for early testing, with dependency upgrades across AWS CloudWatch, Spectator Atlas, Google auth and Google Cloud Monitoring. The 1.17.2 and 1.16.8 maintenance releases ship bug fixes for whitespace in HTTP Basic authentication passwords, a missing reflection hint for getProcessCpuTime, JMS session results proxied using the method's declared return type, and Kotlin interoperability for CaffeineCacheMetrics. AtlasMeterRegistry now publishes FunctionTimer count and totalTime as rates rather than gauge measurements.

This week: HTTP Basic auth no longer trims passwords, so whitespace is preserved. The StatsD UDP server stops logging a warning per packet when the server is down on Linux. The OSGi test runs against the current Prometheus client again, and compiler warnings are cleared on main a

This week's changes to Micrometer: HTTP Basic authentication now preserves whitespace in passwords. withBasicAuthentication previously trimmed the password before encoding the Authorization header, so " secret " was sent as "secret" and a single-space password became empty. The StatsD UDP server no longer logs a warning for every packet when the server is down on Linux (epoll), where each packet raised a PortUnreachableException and an unsubscribed inbound side produced a repeated warning. The OSGi test runs against the current Prometheus client again, with two of the three blockers fixed here. Compiler and Error Prone warnings were also resolved on main and 1.17.x after the forward-merges.

Clean build output work landed this week: CI no longer suppresses warnings, deprecation and unchecked warnings are resolved across modules, and Error Prone issues in production and test code are fixed.

This week the project continued its clean build output initiative. CI warning suppression was removed so local and CI builds enforce warnings the same way. Compiler deprecation and unchecked warnings were resolved across modules, including SimpleObservation generics and ObservationConvention parameterization in tests. Error Prone warnings in test code were cleaned up, and bug patterns in production code were fixed with default branches for non-exhaustive enum switches and targeted suppressions. ModifiedClassPathClassLoader was also updated to the latest upstream version.

Micrometer reduced build output noise, clarified custom resolver documentation, and consolidated license header checking directives for a smoother development experience.

Micrometer addressed build quality this week with multiple improvements: reduced tooling noise by consolidating version logging, configured Error Prone to suppress intentional API patterns, clarified that custom MeterTag resolvers are application-provided, and introduced new license header directives for better file control. These changes create a cleaner development experience for contributors and users.

Micrometer now supports custom JMS observation conventions, adds JVM memory-after-GC metrics, refactors meter conventions for better Spring Boot integration, and makes active LongTaskTimer opt-in.

This week's Micrometer updates focus on improved instrumentation customization and standards alignment. JMS instrumentation gains custom observation convention support, new gauges measure JVM memory pool usage after garbage collection per OpenTelemetry specs, and meter conventions are refactored to use per-convention interfaces. Active observation LongTaskTimer becomes opt-in by default, TomcatMetrics gains HTTP/2 support, and deprecated modules are cleaned up.