Java Ecosystem Evolves: Spring gRPC, Quarkus, and Gatherers4j Push Stream Processing Forward

The Java ecosystem kicked off 2026 with a series of targeted maintenance releases that address real-world developer pain points while pushing forward on modern stream processing capabilities. This week's updates span from enterprise authentication with Keycloak to Kubernetes operator development, but the most significant developments center on Spring gRPC's first maintenance release and the expanding capabilities of Gatherers4j.

Spring gRPC Bridges the Gap Between Reactive and Blocking Worlds

Spring gRPC 1.0.1 marks the first maintenance release for the framework that brings gRPC support into the Spring ecosystem. While the version number suggests incremental progress, the updates address fundamental integration challenges that developers have been wrestling with since the initial release.

The most practical enhancement is the ability to use getContext() from Spring Security's SecurityContextHolder within gRPC-specific Kotlin coroutines. This might sound like a minor detail, but it solves a critical authentication flow problem. In traditional Spring MVC applications, security context propagation across threads is well-established. However, gRPC's persistent connection model combined with Kotlin's coroutine dispatchers creates scenarios where security context can be lost or misaligned.

Consider a typical microservice that needs to authenticate requests flowing through gRPC streams. Previously, developers had to manually propagate security context or build custom interceptors. With this fix, the context becomes available naturally within coroutine scopes, allowing for cleaner code that aligns with Spring Security's standard patterns.

The release also improves error messaging around tracing. When distributed tracing fails or produces incomplete spans, the new error messages provide more diagnostic information. This matters because gRPC services often form the backbone of microservice communication, and when tracing breaks, it becomes nearly impossible to debug production issues across service boundaries.

Quarkus Addresses JDK Flight Recorder Integration

Quarkus 3.30.6 resolves a particularly nasty NullPointerException in the JDK Flight Recorder extension that occurred during shutdown. The bug manifested when the extension attempted to emit runtime information as the application was shutting down, creating a race condition that could crash the JVM before proper cleanup.

This fix is more important than it might appear. Quarkus applications frequently run in containerized environments where graceful shutdown is critical. A crash during shutdown can leave resources dangling, cause incomplete metric collection, and trigger unnecessary restart alerts in orchestration platforms.

The release also marks the end of an era for the official LZ4 Java project. Oracle's discontinuation of the org.lz4:lz4-java project in late 2025 forced the community to seek alternatives. Quarkus now recommends the fork maintained by Oracle's Jonas Konrad at at.yawk.lz4:lz4-java. This transition highlights a broader pattern in the Java ecosystem: as official maintenance of critical libraries wanes, community forks often step in to fill the gap, but they require careful vetting and migration planning.

Gatherers4j Expands Stream Processing Arsenal

Gatherers4j 0.13.0 represents the most significant functional addition in this roundup. Building on JEP 485 (Stream Gatherers) delivered in JDK 24, this release adds sophisticated windowing and aggregation operations that were previously only available through third-party libraries like Reactor or Akka Streams.

The new uniquelyOccurringBy() method addresses a common data processing need: filtering a stream to retain only elements that appear exactly once according to some key function. Imagine processing user events where you want to identify actions that happened exactly once during a session, or analyzing transaction data to find unique purchases. Before this, developers would need to collect to a map, count occurrences, then filter—a verbose and inefficient process.

More compelling are the new moving and running operations: movingMedian(), runningMedian(), movingMax(), movingMin(), and their By() variants that accept custom comparators. These operations enable real-time analytics directly within standard Java streams without requiring external libraries.

The distinction between "moving" and "running" is crucial:

• Moving operations calculate over a fixed-size sliding window. For example, movingMedian(5) would calculate the median of the last 5 elements at each position.
• Running operations calculate over all elements seen so far from the beginning of the stream.

This capability transforms how developers can approach data processing in Java. Previously, calculating a moving median required either manual window management with stateful operations or pulling in heavy reactive streams dependencies. Now it's a single method call.

Todd Ginsberg, who introduced Gatherers4j in July 2024, has effectively brought functional reactive patterns into the standard Java stream model. The library's design respects JDK 24's Stream Gatherers API, which allows custom intermediate operations without breaking the stream pipeline abstraction.

Keycloak Modernizes Token Authentication

Keycloak 26.5.0 introduces JWT Authorization Grant support, implementing RFC 7523. This specification enables OAuth 2.0 clients to authenticate using externally signed JWT assertions rather than traditional client secrets or mutual TLS.

The practical value emerges in enterprise scenarios where services need to authenticate across organizational boundaries. Instead of sharing secrets or managing certificate infrastructure, a client can present a JWT signed by a trusted authority. This pattern aligns with zero-trust architectures and simplifies credential rotation.

The release also enhances OpenTelemetry integration by adding log export capabilities and metrics export through the Quarkus Micrometer extension. For teams running Keycloak in production, this means better observability without custom instrumentation.

Grails and Java Operator SDK Maintenance

Grails 7.0.5 and Java Operator SDK 5.2.2 both received maintenance updates focusing on stability and testing improvements. Grails removed the long-deprecated tomcat-embed-logging-log4j module, which hasn't seen updates since 2016. This cleanup reduces security surface area and dependency conflicts.

Java Operator SDK's integration testing improvements using @Sample annotations demonstrate the framework's maturation. Kubernetes operator development requires careful state management and reconciliation logic, so enhanced testing utilities directly translate to more reliable operators in production.

JDK 26 and 27 Early Access Progress

The early-access builds continue their march forward. JDK 26 Build 30 and JDK 27 Build 4 are available for testing, though the release notes only mention general bug fixes. For developers evaluating future JDK versions, these builds provide the opportunity to test compatibility and discover potential issues before GA releases.

Looking Forward

This week's releases demonstrate a Java ecosystem that's maturing beyond flashy features into practical, production-ready tooling. Spring gRPC is stabilizing its integration points, Quarkus is hardening its observability stack, and Gatherers4j is bringing sophisticated stream processing into reach of standard Java developers.

The common thread is reducing friction in everyday development tasks. Whether it's propagating security context through coroutines, calculating moving medians without external dependencies, or debugging shutdown crashes, these updates address the accumulated friction points that slow down real-world development.

For teams running Java in production, these releases warrant immediate evaluation. The Gatherers4j update in particular could justify eliminating reactive streams dependencies in applications that only needed them for windowing operations, potentially simplifying the technology stack and reducing memory footprint.

Michael Redlich has been an active member of the Java community for 25 years and leads the Garden State Java User Group. He serves as a Java community news editor for InfoQ and is a committer on Jakarta NoSQL and Jakarta Data specifications.