feat: upgrade Java compilation target from 17 to 21

[soul2zimate]

• Update maven.compiler.release from 17 to 21 in pom.xml
• Update CI PR workflow MAIN_JAVA_VER to 21 and simplify test matrix
• Update CI release workflow to use Java 21
• Add Java 21 minimum requirement to README
• Revise Known Issues section for Java 17 hang warning

Implements TC-3969

Assisted-by: Claude Code

[qodo-code-review]

Review Summary by Qodo

Upgrade Java compilation target to version 21

✨ Enhancement

Walkthroughs

Description

• Upgrade Java compilation target from 17 to 21
• Simplify CI test matrix to only Java 21
• Update CI workflows to use Java 21
• Add Java 21 minimum requirement documentation
• Revise Known Issues section for Java 17 compatibility

Diagram

flowchart LR
  pom["pom.xml<br/>maven.compiler.release: 17→21"]
  pr_workflow["pr.yml<br/>MAIN_JAVA_VER: 17→21<br/>matrix: [17,21]→[21]"]
  release_workflow["release.yml<br/>java-version: 17→21"]
  readme["README.md<br/>Add Java 21 requirement<br/>Update Known Issues"]
  pom --> pr_workflow
  pom --> release_workflow
  pom --> readme

Loading

File Changes

1. pom.xml ⚙️ Configuration changes +1/-1

Update Maven compiler release to Java 21

• Update maven.compiler.release property from 17 to 21
• Aligns project compilation target with new minimum Java version requirement

pom.xml

---

2. .github/workflows/pr.yml ⚙️ Configuration changes +2/-2

Simplify PR workflow to Java 21 only

• Update MAIN_JAVA_VER environment variable from 17 to 21
• Simplify test matrix from [17, 21] to [21] only
• Reduces CI test redundancy by removing Java 17 testing

.github/workflows/pr.yml

---

3. .github/workflows/release.yml ⚙️ Configuration changes +2/-2

Update release workflow to Java 21

• Update Java setup step from version 17 to 21
• Update java-version parameter in actions/setup-java@v5 action
• Ensures release builds use Java 21

.github/workflows/release.yml

---

View more (1)

4. README.md 📝 Documentation +5/-4

Add Java 21 requirement and update documentation

• Add prominent notice requiring Java 21 or later at top of README
• Revise Known Issues section to reflect Java 21 minimum requirement
• Update Java 17 hang warning to clarify issue is now resolved
• Minor grammar improvements in Known Issues documentation

README.md

---

[qodo-code-review]

Code Review by Qodo

🐞 Bugs (0) 📘 Rule violations (0) 📎 Requirement gaps (0)

1. Enforcer JDK mismatch ☑ 🐞 Bug ☼ Reliability

Description

pom.xml now compiles with maven.compiler.release=21, but the Maven Enforcer rule still allows Java
[11,), so builds on JDK 11–20 will pass validate and then fail later during compilation with a
less actionable error.

Code

pom.xml[19]

+    <maven.compiler.release>21</maven.compiler.release>

Evidence

The project is configured to compile for Java 21, but the enforcer rule does not enforce Java 21+
and will accept older JDKs, causing late-stage compilation failures instead of an early, clear
validation failure.

pom.xml[14-21]
pom.xml[610-636]

Agent prompt

The issue below was found during a code review. Follow the provided context and guidance below and implement a solution

## Issue description
The build is configured for Java 21 bytecode (`maven.compiler.release=21`), but Maven Enforcer still permits running Maven with JDK 11–20 (`requireJavaVersion` is `[11,)`). This causes validation to succeed and compilation to fail later with a less helpful error.

## Issue Context
With `maven.compiler.release=21`, compiling requires JDK 21+.

## Fix Focus Areas
- pom.xml[610-636]
- pom.xml[14-21]

## Suggested change
Update the enforcer rule to require Java 21+ (e.g., `<version>[21,)</version>`).

ⓘ Copy this prompt and use it to remediate the issue with your preferred AI generation tools

---

2. Contributing badge outdated ☑ 🐞 Bug ⚙ Maintainability

Description

README now states Java 21 is required, but CONTRIBUTING.md still advertises a Java Version 11 badge,
which misleads contributors about prerequisites.

Code

README.md[R6-7]

+**Requires Java 21 or later.**
+

Evidence

The README explicitly declares Java 21+ as the minimum, while CONTRIBUTING.md’s badge link still
points to Java Version 11, making project documentation inconsistent post-upgrade.

README.md[1-10]
CONTRIBUTING.md[111-116]

Agent prompt

The issue below was found during a code review. Follow the provided context and guidance below and implement a solution

## Issue description
CONTRIBUTING.md still shows a Java Version 11 badge even though the project now requires Java 21+.

## Issue Context
README.md was updated to state the new minimum Java version.

## Fix Focus Areas
- CONTRIBUTING.md[111-116]
- README.md[1-10]

## Suggested change
Update the badge URL in CONTRIBUTING.md to reflect Java 21 (change the `/11/` portion of the badgen URL to `/21/`).

ⓘ Copy this prompt and use it to remediate the issue with your preferred AI generation tools

---

ⓘ The new review experience is currently in Beta. Learn more

[soul2zimate]

@ruromero Could you go to Settings → Branches → Branch protection rules → main → Edit to remove the required job rule for Build and test Java 17 Thanks.

[ruromero]

Could you go to Settings → Branches → Branch protection rules → main → Edit to remove the required job rule for Build and test Java 17 Thanks.

I can't but I have asked one of the Org maintainers

[ruromero]

All looks good

[qodo-code-review]

Code Review by Qodo

🐞 Bugs (0) 📘 Rule violations (0) 📎 Requirement gaps (0)

1. Enforcer JDK mismatch ☑ 🐞 Bug ☼ Reliability

Description

pom.xml now compiles with maven.compiler.release=21, but the Maven Enforcer rule still allows Java
[11,), so builds on JDK 11–20 will pass validate and then fail later during compilation with a
less actionable error.

Code

pom.xml[19]

+    <maven.compiler.release>21</maven.compiler.release>

Evidence

The project is configured to compile for Java 21, but the enforcer rule does not enforce Java 21+
and will accept older JDKs, causing late-stage compilation failures instead of an early, clear
validation failure.

pom.xml[14-21]
pom.xml[610-636]

Agent prompt

The issue below was found during a code review. Follow the provided context and guidance below and implement a solution

## Issue description
The build is configured for Java 21 bytecode (`maven.compiler.release=21`), but Maven Enforcer still permits running Maven with JDK 11–20 (`requireJavaVersion` is `[11,)`). This causes validation to succeed and compilation to fail later with a less helpful error.

## Issue Context
With `maven.compiler.release=21`, compiling requires JDK 21+.

## Fix Focus Areas
- pom.xml[610-636]
- pom.xml[14-21]

## Suggested change
Update the enforcer rule to require Java 21+ (e.g., `<version>[21,)</version>`).

ⓘ Copy this prompt and use it to remediate the issue with your preferred AI generation tools

---

2. Contributing badge outdated ☑ 🐞 Bug ⚙ Maintainability

Description

README now states Java 21 is required, but CONTRIBUTING.md still advertises a Java Version 11 badge,
which misleads contributors about prerequisites.

Code

README.md[R6-7]

+**Requires Java 21 or later.**
+

Evidence

The README explicitly declares Java 21+ as the minimum, while CONTRIBUTING.md’s badge link still
points to Java Version 11, making project documentation inconsistent post-upgrade.

README.md[1-10]
CONTRIBUTING.md[111-116]

Agent prompt

The issue below was found during a code review. Follow the provided context and guidance below and implement a solution

## Issue description
CONTRIBUTING.md still shows a Java Version 11 badge even though the project now requires Java 21+.

## Issue Context
README.md was updated to state the new minimum Java version.

## Fix Focus Areas
- CONTRIBUTING.md[111-116]
- README.md[1-10]

## Suggested change
Update the badge URL in CONTRIBUTING.md to reflect Java 21 (change the `/11/` portion of the badgen URL to `/21/`).

ⓘ Copy this prompt and use it to remediate the issue with your preferred AI generation tools

---

ⓘ The new review experience is currently in Beta. Learn more