java-checkstyle - SKILL.md Agent Skill

name: java-checkstyle description: Run `mvn spotless:apply` to fix Java checkstyle / formatting failures and verify the result. Invoke after authoring or modifying any `.java` files, or when CI reports a "Java checkstyle failed" or "Fix Java checkstyle" issue on a PR. user-invocable: true argument-hint: "[-pl ] [--check]" allowed-tools: - Bash - Read - Grep - Glob

Java Checkstyle / Spotless

OpenMetadata enforces Java formatting via the Spotless Maven plugin. Every CI build runs mvn spotless:check and fails the PR if any file is not formatted. This skill keeps the fix on a single, consistent command so reviewers never have to ask for it manually again.

When to activate

The user asks to "fix checkstyle", "fix Java formatting", "apply spotless", "run spotless", "format Java", or similar.
CI posts a Java checkstyle failed / Fix Java checkstyle comment on a PR (the project's bot phrases the instruction as "Please run mvn spotless:apply in the root of your repository and commit the changes").
After the assistant has finished authoring or editing any .java files — before opening a PR or pushing a commit that touches Java.

Arguments

No arguments: run mvn spotless:apply at the repo root across all modules.
-pl <module>: scope to a single Maven module (e.g. -pl openmetadata-service). Useful when only one module changed and you want a faster run.
--check: run mvn spotless:check instead of apply. Use to confirm the tree is clean without touching files (e.g. to verify before push).

Process

Step 1: Run Spotless

From the repo root:

mvn spotless:apply                 # default — formats everything
# or
mvn -pl <module> spotless:apply    # scoped to one module
# or
mvn spotless:check                 # verify only, don't write

Spotless is fast (seconds, no compilation). If it fails with a plugin error (not a formatting diff), surface the error and stop — do not try to hand-edit formatting around the failure.

Step 2: Check what changed

git status --short
git diff --stat

Expect reformatting in .java files only. If Spotless touches pom.xml or other non-Java files, that's also fine — Spotless is configured for those too in this repo.

Step 3: Stage and commit (only if the user asked to commit)

Do NOT auto-commit. Report the changed file list to the user and let them decide whether to fold the formatting into the in-progress commit or make a separate "Fix Java checkstyle" commit. Follow the repo convention: the existing branch history already uses Fix Java checkstyle as the commit title for bot-triggered formatting-only commits.

Notes

Spotless config lives in the root pom.xml (spotless-maven-plugin section). Do not redefine formatting rules inline in source files.
If Spotless keeps rewriting a change the user just made, re-read the config — Spotless is the source of truth, not the IDE.
The analogous UI command is yarn pretty (see the test-locally skill / CLAUDE.md for the UI lint flow); this skill is Java-only.