Episode 101 of the Foojay Podcast.

JDK 27 arrives on 15 September 2026 without finalising a single new piece of language syntax. It is still worth the upgrade: object headers shrink from 64 bits to 32, which the JEP measures at 22% less heap and 8% less CPU on SPECjbb2015, and G1 becomes the default garbage collector on every machine. Both changes live inside the JVM, so an application you compiled years ago picks them up with no code change at all.

Simon Ritter, Deputy CTO at Azul and Java Champion, takes us through all nine JEPs in the release, explains why a non-LTS version is still worth testing against, and makes the point that "long-term support" describes the binary you download rather than anything in OpenJDK itself. We also cover the move from quarterly to monthly security updates that started in August 2026, and then look ahead to March 2027, when Project Valhalla reaches its first preview after roughly twelve years of work.

Topics include:

• Compact object headers by default, and what 22% less heap actually buys you in production
• Post-quantum key exchange in TLS 1.3, and the harvest-now-decrypt-later attack it defends against
• JFR redaction: keeping access tokens and passwords out of flight recordings you share
• Structured concurrency in its seventh preview, and why an evolving API stays in preview
• The Vector API's twelfth incubation, and what it is waiting for
• Value Objects in Java 28: a new value keyword, 179,000 lines, 1,800 files, and why it will not be final in JDK 29
• Whether a Simple JSON API in the JDK will survive its previews, or go the way of string templates

Guest: Simon Ritter
Deputy CTO at Azul, Java Champion
Simon on LinkedIn
Simon on Foojay

Links:
Full show notes, with every JEP linked
JDK 27
What CSPUs Mean for Your Release Pipeline
What to Know About Garbage Collection as a Java Developer!
Project Valhalla

Timestamps:
00:00 Introduction of the topic and guest
01:27 How long Simon has been doing Java
01:54 Why release 27 is important, even when not being a Long Term Support release
04:55 Quarterly and monthly security updates between new version releases
08:07 Which JVM versions are most used in companies
09:23 JEP 534: Compact Object Headers by Default
14:51 JEP 523: Make G1 the Default Garbage Collector in All Environments
18:59 JEP 527: Post-Quantum Hybrid Key Exchange for TLS 1.3
22:55 JEP 538: PEM Encodings of Cryptographic Objects (Third Preview)
25:35 JEP 536: JFR In-Process Data Redaction
28:02 JEP 531: Lazy Constants (Third Preview)
29:55 JEP 532: Primitive Types in Patterns, instanceof, and switch (Fifth Preview)
33:13 JEP 533: Structured Concurrency (Seventh Preview)
38:21 JEP 537: Vector API (Twelfth Incubator)
40:28 Looking forward to Java 28 and Project Valhalla
42:31 JEP 401: Value Objects and JEP 539: Strict Field Initialization
47:36 Can we expect this to be finalized in Java 29?
48:26 LTS releases every 1, 2, or 3 years?
49:55 JEP 541: Deprecate macOS/x64
51:53 JEP 540: Simple JSON API (Incubator)
55:30 Conclusion, what to remember from this release

Episode 100 of the Foojay Podcast. No grand plan. It just happened.

To mark the milestone, Frank turned the microphone around and invited other podcasters: Adam Bien (airhacks.fm), Jennifer Reif (Breaktime Tech Talks), Kadi McKean and Steve Pool (10xInsights), and Oumaima Zerouali (JCast). Same questions for each: why did you start, what broke, and what did you learn?

Along the way: why a no-prep podcast works when you have 20 years of experience, the difference between writing a blog and recording a podcast, burnout from editing, AI tools that changed someone's voice into Batman, and why a Dutch Java podcast about the human side of development got its first episode from a calendar invite that became a recording.

Guests:

• Adam Bien — airhacks.fm
• Jennifer Reif — Breaktime Tech Talks
• Kadi McKean and Steve Pool — 10xInsights
• Oumaima Zerouali — JCast

• 
  

Links:

• airhacks.fm on Spotify
• Breaktime Tech Talks on Spotify
• 10xInsights | 10xInsights on Spotify
• JCast
• Foojay Podcast #67: Writing a book. Does it make you rich and famous?
• Foojay Podcast #71: 30 Years of Java with James Gosling
• Foojay Podcast #99: Testing the Untestable: LLM Security for Java Developers with Tiberius
• Frank on JCast
• Other podcasts mentioned:
• Spring Documentary

Content:

00:00 Introduction

01:00 Adam Bien (airhacks.fm)

12:52 Jennifer Reif (Breaktime Tech Talks)

26:25 Kadi McKean and Steve Pool (10xInsights)

38:43 Quote by James Gosling

39:46 Oumaima Zerouali (JCast)

48:01 Conclusion

Hosted by Frank Delporte | foojay.io

Your Java AI application is live in production. But have you tested whether it can be jailbroken, manipulated into revealing its system prompt, or tricked into printing content it should never output?

In this episode, Iryna Dohndorf, Software Engineer at Karakun Group and creator of Tiberius, explains how to bring security testing to LLM-powered Java applications. We cover why traditional unit tests break down with non-deterministic systems, how the Scan-Fixture-Validate workflow works, what buff mutation testing is, and why even well-trained models can be cracked with something as simple as the grandmother attack.

Topics include:

• Why LLM non-determinism breaks the classic input/output test model
• The Scan-Fixture-Validate principle and sharing test artifacts across teams
• Prompt injection, jailbreaks, and emotional manipulation attacks
• Buff mutation: testing linguistic surface coverage
• Probabilistic security contracts and multi-trial scans
• Fingerprinting and why your model choice should not be detectable
• LLM as a judge: using a second model as a guardrail
• Getting started with Tiberius in Spring Boot and LangChain4j

Guest
Iryna Dohndorf - Software Engineer at Karakun Group
LinkedIn

Links
Article on Foojay
Tiberius on GitHub
Security Testing Guide

Timestamps
00:00 Introduction of topic and guest
01:05 The problem Tiberius wants to solve
06:39 How "traditional" unit tests don't work for LLM integrations
10:23 Scan-Fixture-Validate principle and sharing artifacts
15:15 Using different skills, for example, the grandmother skill
17:33 Testing for required versus forbidden bias
19:35 The probes across nine attack categories used by Tiberius
20:44 Buff mutation testing
26:55 Using Tiberius in your pipelines and when to fail
29:35 Using multi-trial scans
31:14 Fingerprinting: which model you use, should not be detectable
32:55 Combining multiple models, model as a judge
34:41 Sharing JSON models to improve tests
36:05 How to get started with Tiberius in Spring and with LangChain4j
36:41 Quarkus not supported yet, plans for the future
39:07 Conclusions and a call out to everyone to become a Foojay author