java-checkstyle

# 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 to this PR"). - After you have 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: ```bash 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 ```bash 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: Commit Do not fold the reformat into an unrelated commit. If the user asked you to commit, follow their preference (fold into the in-progress commit, or make a separate one). Otherwise, when you are confident the change is a purely mechanical formatting reformat, you may commit it on its own as a `Fix Java checkstyle` commit — this matches the repo's existing history for bot-triggered formatting-only commits. If you are unsure whether the diff is purely mechanical, do NOT auto-commit: surface the changed-file list and let the user decide. ## Notes - Spotless config lives in the root `pom.xml` (`spotless-maven-plugin` section) — `googleJavaFormat` + `removeUnusedImports`. Do not redefine formatting rules inline in source files. - If Spotless keeps rewriting a change you just made, re-read the config — Spotless is the source of truth, not the IDE. - CI enforcement lives in `.github/workflows/java-checkstyle.yml`: the `java-checkstyle` job runs `mvn spotless:apply` and fails (`git diff-files`) if the tree was not already formatted, posting the "Please run `mvn spotless:apply`" comment. ## Out of scope - UI / TypeScript formatting — use the `ui-checkstyle` skill (ESLint + Prettier + organize-imports); this skill is Java-only. - Python formatting — use `make py_format` (**ruff** lint-fix + format; see `ingestion/Makefile`). *(Note: this is ruff, not black/isort/pycln.)*