Use Gradle Worker API for R8 minimization

[Goooler]

Refs:

• https://docs.gradle.org/current/userguide/worker_api.html
• https://github.com/Goooler/agp-sources/blob/d383e6c2d704f6f93397fceb9a424e0082dfa164/9.3.1/com.android.tools.build/gradle/com/android/build/gradle/internal/tasks/R8Task.kt#L327-L337
• https://github.com/Goooler/agp-sources/blob/d383e6c2d704f6f93397fceb9a424e0082dfa164/9.3.1/com.android.tools.build/gradle/com/android/build/gradle/internal/tasks/R8Task.kt#L523-L579

---

• CHANGELOG's "Unreleased" section has been updated, if applicable.

[Copilot]

Pull request overview

This PR migrates R8-based minimization from direct ExecOperations.javaexec invocation to the Gradle Worker API, aiming to improve isolation and align with Gradle’s preferred execution model for heavy tools.

Changes:

• Inject WorkerExecutor into ShadowJar and route R8 minimization through it.
• Replace ExecOperations.javaexec R8 execution with a WorkAction-based implementation.
• Document the change in the Unreleased changelog and update the Kotlin ABI dump to reflect the new protected accessor.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/tasks/ShadowJar.kt	Injects WorkerExecutor, deprecates ExecOperations, and passes the executor into R8 minimization.
src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/internal/R8Minimizer.kt	Reworks R8 invocation to run via a Gradle worker and introduces R8WorkAction.
docs/changes/README.md	Adds an Unreleased entry describing the Worker API migration for R8 minimization.
api/shadow.api	Updates ABI dump to include the new protected getWorkerExecutor() accessor.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated no new comments.

Suppressed comments (3)

src/functionalTest/kotlin/com/github/jengelman/gradle/plugins/shadow/MinimizeTest.kt:701

• Using single { ... } makes this functional test flaky if Gradle logs multiple worker daemon startups (or duplicates the line). Prefer selecting the first matching line instead.

    val workerCommand =
      result.output.lineSequence().single { "Starting process 'Gradle Worker Daemon" in it }
    assertThat(workerCommand).contains("-Xmx640m")

src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/tasks/R8Spec.kt:21

• KDoc says the value uses JVM memory notation (e.g. 512m), but the default value is set from Runtime.getRuntime().maxMemory().toString() (a raw byte count). Clarify in the documentation that a plain byte count is also accepted (or adjust the default to match the documented notation).

   * Defaults to the effective maximum heap size of the Gradle daemon. The value uses JVM memory
   * notation, such as `2g` or `512m`.

src/functionalTest/kotlin/com/github/jengelman/gradle/plugins/shadow/MinimizeTest.kt:679

• Using single { ... } makes this functional test flaky if Gradle logs multiple worker daemon startups (or duplicates the line). Prefer selecting the first matching line instead.

This issue also appears on line 699 of the same file.

    val workerCommand =
      result.output.lineSequence().single { "Starting process 'Gradle Worker Daemon" in it }
    assertThat(workerCommand).contains("-Xmx${768L * 1024 * 1024}")

[Goooler]

Based on Goooler/ktfmt@4d98e5b:

Summary Statistics

Statistic	profile-out-3 (ms)	profile-out-4 (ms)	Difference (ms)	Difference (%)
Mean	32,726.33	32,384.99	-341.34	-1.04%
Median	31,953.24	31,414.15	-539.09	-1.69%
Min	30,163.83	29,998.68	-165.15	-0.55%
Max	37,554.65	36,146.37	-1,408.28	-3.75%
Std Dev	2,223.96	2,206.81	-17.15	-0.77%
Total Measured Time	327,263.25	323,849.86	-3,413.39	-1.04%

[Goooler]

No need to land this for now.