Remove the gradle-wrapper.jar

[MrAlias]

Stop tracking the binary Gradle wrapper JAR in git history. Update the Gradle wrapper JAR/workflow from the Java integration and standardizes builds on the host/container gradle CLI.

Changes

• Removed wrapper artifacts/scripts from pkg/internal/java (gradle-wrapper.jar, gradlew, gradlew.bat, wrapper properties).
• Updated Java build/test/format paths to use gradle directly in:
  • .github/workflows/java-agent.yml
  • Makefile
  • Dockerfile
  • javaagent.Dockerfile
  • internal/test/integration/components/obi/Dockerfile-with-javaagent
• Updated Java docs to reflect current prerequisites and build commands:
  • pkg/internal/java/README.md
  • pkg/internal/java/agent/src/jmh/.../BENCHMARK_README.md
• Refreshed embedded Java agent artifact: pkg/internal/java/embedded/obi-java-agent.jar.

Fixes

Added fix for Java 8 CI correctness by enforcing Java 8 API targeting at compile time (options.release = 8 in the Java Gradle config). This prevents newer-JDK method signatures from leaking into compiled classes (e.g., ByteBuffer.flip()/position() return types), which caused NoSuchMethodError when tests were executed on JDK 8. The Java 8 matrix path now runs successfully with Gradle on the pinned JDK and tests on the matrix JDK.

Validation

• Java notices are up to date (make java-notices-update produced no diffs).
• Updated Docker build paths were validated by building changed Docker targets successfully.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 43.90%. Comparing base (cc5693e) to head (5ac8851).
⚠️ Report is 11 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1461   +/-   ##
=======================================
  Coverage   43.90%   43.90%           
=======================================
  Files         313      313           
  Lines       34213    34213           
=======================================
  Hits        15022    15022           
  Misses      18213    18213           
  Partials      978      978           

Flag	Coverage Δ
integration-test	21.71% <ø> (-0.04%)	⬇️
integration-test-arm	0.00% <ø> (ø)
integration-test-vm-x86_64-5.15.152	0.00% <ø> (ø)
integration-test-vm-x86_64-6.10.6	0.00% <ø> (ø)
k8s-integration-test	2.29% <ø> (ø)
oats-test	0.00% <ø> (ø)
unittests	44.89% <ø> (ø)

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[MrAlias]

@grcevski thoughts?

[Copilot]

Pull request overview

This PR removes the Gradle wrapper artifacts from the embedded Java agent project and updates build/CI/Docker/documentation to use the host/container gradle CLI instead, reducing tracked binary wrapper files in the repo.

Changes:

• Removed Gradle wrapper scripts/config (including the tracked wrapper JAR) from pkg/internal/java.
• Updated CI, Make targets, and Docker build steps to invoke gradle directly.
• Updated Java agent docs/benchmark docs to reflect the new build prerequisites/commands, and refreshed the embedded agent JAR.

Reviewed changes

Copilot reviewed 10 out of 12 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
pkg/internal/java/gradlew.bat	Removed Windows Gradle wrapper script.
pkg/internal/java/gradlew	Removed POSIX Gradle wrapper script.
pkg/internal/java/gradle/wrapper/gradle-wrapper.properties	Removed wrapper configuration (no longer pinning Gradle via wrapper).
pkg/internal/java/gradle/wrapper/gradle-wrapper.jar	Removed tracked wrapper binary.
pkg/internal/java/agent/src/jmh/java/io/opentelemetry/obi/java/instrumentations/util/BENCHMARK_README.md	Updated benchmark commands to use gradle (needs minor doc clarification).
pkg/internal/java/README.md	Updated prerequisites and build commands for wrapper-less workflows.
.github/workflows/java-agent.yml	Switched CI steps from ./gradlew to gradle.
Makefile	Switched Java targets from wrapper to gradle and added JAVA_HOME selection based on .java-version.
Dockerfile	Switched Java agent build step from wrapper to gradle.
javaagent.Dockerfile	Switched Java agent build step from wrapper to gradle.
internal/test/integration/components/obi/Dockerfile-with-javaagent	Switched integration image Java agent build step from wrapper to gradle.
pkg/internal/java/embedded/obi-java-agent.jar	Refreshed embedded agent artifact (binary update).

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[MrAlias]

Looks like Java 8 testing wasn't actually testing against Java 8. Pushed a fix here.

[grcevski]

LGTM! Yeah we should remove them, the build will make them anyway.