Add OpenRewrite recipe for JEP 512 instance main methods #852
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Implements a migration recipe to convert `public static void main(String[] args)` to instance `void main()` when the args parameter is unused, as introduced in JEP 512 (Java 21+). The recipe: - Detects main methods with unused String[] args parameter - Removes public and static modifiers - Removes the unused parameter - Preserves formatting and annotations - Only applies to Java 21+ codebases 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com>
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src/main/java/org/openrewrite/java/migrate/lang/MigrateMainMethodToInstanceMain.java
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src/main/java/org/openrewrite/java/migrate/lang/MigrateMainMethodToInstanceMain.java
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src/main/java/org/openrewrite/java/migrate/lang/MigrateMainMethodToInstanceMain.java
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Refactored the modifier filtering logic to use OpenRewrite's ListUtils.filter and ListUtils.mapFirst utilities for cleaner and more idiomatic code.
src/main/java/org/openrewrite/java/migrate/lang/MigrateMainMethodToInstanceMain.java
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Oct 7, 2025
…17.1 to 3.18.0 [skip ci] [//]: # (dependabot-start)⚠️ \*\*Dependabot is rebasing this PR\*\*⚠️ Rebasing might not happen immediately, so don't worry if this takes some time. Note: if you make any changes to this PR yourself, they will take precedence over the rebase. --- [//]: # (dependabot-end) Bumps [org.openrewrite.recipe:rewrite-migrate-java](https://github.com/openrewrite/rewrite-migrate-java) from 3.17.1 to 3.18.0. Release notes *Sourced from [org.openrewrite.recipe:rewrite-migrate-java's releases](https://github.com/openrewrite/rewrite-migrate-java/releases).* > 3.18.0 > ------ > > What's Changed > -------------- > > * Add OpenRewrite recipe for JEP 512 instance main methods by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#852](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/852) > * Generate Guava InlineMethodCalls recipes using [openrewrite/rewrite#6059](https://redirect.github.com/openrewrite/rewrite/issues/6059) by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#853](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/853) > * Run CI on Java 25 by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#851](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/851) > * Generate recipes for Guava 33.5.0-jre by [`@timtebeek`](https://github.com/timtebeek) in [openrewrite/rewrite-migrate-java#854](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/854) > * Use type tables for tests by [`@knutwannheden`](https://github.com/knutwannheden) in [openrewrite/rewrite-migrate-java#856](https://redirect.github.com/openrewrite/rewrite-migrate-java/pull/856) > > **Full Changelog**: <openrewrite/rewrite-migrate-java@v3.17.1...v3.18.0> Commits * [`5a66684`](openrewrite/rewrite-migrate-java@5a66684) Use type tables for tests ([#856](https://redirect.github.com/openrewrite/rewrite-migrate-java/issues/856)) * [`1111d4a`](openrewrite/rewrite-migrate-java@1111d4a) Migrate away from micrometer nullable annotations * [`257d4bc`](openrewrite/rewrite-migrate-java@257d4bc) Generate recipes for Guava 33.5.0-jre ([#854](https://redirect.github.com/openrewrite/rewrite-migrate-java/issues/854)) * [`041816a`](openrewrite/rewrite-migrate-java@041816a) Run CI on Java 25 ([#851](https://redirect.github.com/openrewrite/rewrite-migrate-java/issues/851)) * [`bb024d5`](openrewrite/rewrite-migrate-java@bb024d5) Generate Guava InlineMethodCalls recipes using [openrewrite/rewrite#6059](https://redirect.github.com/openrewrite/rewrite/issues/6059) ([#853](https://redirect.github.com/openrewrite/rewrite-migrate-java/issues/853)) * [`2a1a482`](openrewrite/rewrite-migrate-java@2a1a482) [Auto] SDKMAN! Java candidates as of 2025-09-22T1016 * [`72818ad`](openrewrite/rewrite-migrate-java@72818ad) Add OpenRewrite recipe for JEP 512 instance main methods ([#852](https://redirect.github.com/openrewrite/rewrite-migrate-java/issues/852)) * See full diff in [compare view](openrewrite/rewrite-migrate-java@v3.17.1...v3.18.0) [](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores) Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting `@dependabot rebase`. [//]: # (dependabot-automerge-start) [//]: # (dependabot-automerge-end) --- Dependabot commands and options You can trigger Dependabot actions by commenting on this PR: - `@dependabot rebase` will rebase this PR - `@dependabot recreate` will recreate this PR, overwriting any edits that have been made to it - `@dependabot merge` will merge this PR after your CI passes on it - `@dependabot squash and merge` will squash and merge this PR after your CI passes on it - `@dependabot cancel merge` will cancel a previously requested merge and block automerging - `@dependabot reopen` will reopen this PR if it is closed - `@dependabot close` will close this PR and stop Dependabot recreating it. You can achieve the same result by closing it manually - `@dependabot show ignore conditions` will show all of the ignore conditions of the specified dependency - `@dependabot ignore this major version` will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself) - `@dependabot ignore this minor version` will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself) - `@dependabot ignore this dependency` will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)
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Summary
public static void main(String[] args)to instancevoid main()when args is unusedChanges
Added
MigrateMainMethodToInstanceMainrecipe class that:VariableReferences.findRhsReferences()Comprehensive test suite with 12 test cases covering:
Added recipe to Java 25 migration path (JEP 512 was introduced in Java 21 but is particularly relevant for modern Java)
Test Plan
./gradlew test --tests "*MigrateMainMethodToInstanceMainTest*")Related