Upgrade com.diffplug.spotless 6.2.1 -> 7.2.1 (google-java-format pinned to 1.13.0)

[devin-ai-integration]

Summary

Upgrades only the Spotless Gradle plugin. The formatter itself is pinned to the version Spotless 6.2.1 resolves today, so formatting output is byte-identical and no .java file changes.

 plugins {
-    id "com.diffplug.spotless" version "6.2.1"
+    id "com.diffplug.spotless" version "7.2.1"
 }
 spotless { java {
-        googleJavaFormat()
+        googleJavaFormat('1.13.0')
 } }

Diff is build.gradle only — 2 lines.

Why 7.2.1 and not 6.25.0

The assignment suggested 6.25.0 on the assumption that Spotless 7.x needs Gradle 8+. Verified upstream and empirically, that is not the case:

• Spotless 7.2.1 (released 2025-07-21) plugin-gradle/README.md: "Spotless requires JRE 11+ and Gradle 6.1.1 or newer."
• Spotless 8.0.0 is the version that raises the floor: "BREAKING Bump the required Gradle to 7.3 and required Java to 17" — Java 17 is out of bounds for this repo (Java 11 ceiling), so 7.2.1 is the newest usable release.
• 7.2.1 was exercised here on Gradle 7.4 + JDK 11 with spotlessApply, spotlessCheck and the full gate — all green.

Why the formatter is pinned

Spotless 6.2.1's default google-java-format is 1.13.0 (confirmed empirically: javap -c on the cached spotless-lib-2.22.1.jar GoogleJavaFormatStep shows the constant 1.13.0, and the Gradle cache contains only google-java-format/1.13.0). Spotless 7.2.1's default would be 1.24.0, which reformats the whole source tree. Pinning googleJavaFormat('1.13.0') keeps the output identical while parallel upgrade PRs are open against this repo. A follow-up PR can drop the pin and adopt the newer google-java-format once those have merged (note: gjf 1.25+ requires Java 17, so the follow-up is bounded by the Java 11 ceiling too).

API migration

No source changes needed. The plugin is build-time only; the spotless { java { ... } } DSL used here (target, googleJavaFormat) is unchanged in 7.x, and pinning the formatter version means the format itself did not move.

Version resolution evidence

$ ./gradlew buildEnvironment | grep spotless
\--- com.diffplug.spotless:com.diffplug.spotless.gradle.plugin:7.2.1
     \--- com.diffplug.spotless:spotless-plugin-gradle:7.2.1
          +--- com.diffplug.spotless:spotless-lib:3.3.1
          \--- com.diffplug.spotless:spotless-lib-extra:3.3.1

(The plugin resolves on the buildscript classpath, not runtimeClasspath/testRuntimeClasspath, so buildEnvironment is the applicable insight command; the Spring Boot BOM does not manage it.)

Source-clean check:

$ JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64 ./gradlew spotlessApply
BUILD SUCCESSFUL
$ git status --short
 M build.gradle          # no .java files modified

Negative control — spotlessCheck still enforces under 7.2.1 (appended a deliberately misformatted class to Util.java, ran the check, reverted):

$ ./gradlew spotlessCheck
BUILD FAILED

Gate

$ JAVA_HOME=/usr/lib/jvm/java-11-openjdk-amd64 ./gradlew clean test spotlessCheck -x jacocoTestCoverageVerification
BUILD SUCCESSFUL in 17s
tests 68  failures 0  errors 0  skipped 0

Baseline recorded on untouched main (commit 3037fa5) with the same command: BUILD SUCCESSFUL, tests 68, failures 0, errors 0, skipped 0. Equal test count, zero new failures.

Pre-existing on base, not addressed here

• jacocoTestCoverageVerification fails on main at ~0.33 instruction coverage against the 0.80 rule in build.gradle. CI excludes it (./gradlew clean test -x jacocoTestCoverageVerification) and so does the gate above. Threshold untouched, no tests added to game it.
• The spotlessJava "Execution optimizations have been disabled … uses this output of task ':compileJava' without declaring an explicit or implicit dependency" warnings are present on main before this change as well (a project.fileTree(rootDir) target that overlaps build/); unchanged by the upgrade and out of scope.
• Selenium E2E tests (src/test/java/io/spring/selenium) run under the separate seleniumTest TestNG task and are not part of the gate.

Link to Devin session: https://partner-workshops.devinenterprise.com/sessions/84fae1c4ce184c728f3a79f548562af9
Requested by: @mbatchelor81

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR. Add '(aside)' to your comment to have me ignore it.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment, CI, and merge conflict monitoring