Update errorprone, fix javadoc, switch to Maven Central

[usmansaleem]

Summary

• Update errorprone 2.28.0 → 2.36.0, errorprone-checks 1.1.1 → 1.1.2, errorprone plugin 4.0.1 → 5.1.0
• Fix javadoc warnings (unescaped HTML generics, relax doclint to -Xdoclint:all,-missing)
• Replace Cloudsmith publishing with JReleaser + Maven Central (new coordinates: io.consensys.protocols:discovery)
• Replace grgit with git-versioning plugin, use java.withJavadocJar()/withSourcesJar()
• Update CI workflow: pin actions with SHAs, publish only on tags with JReleaser secrets
• Update README with Maven Central badge and new dependency coordinates

Required manual setup

• Create publish environment in GitHub repo settings
• Add secrets: JRELEASER_MAVENCENTRAL_USERNAME, JRELEASER_MAVENCENTRAL_PASSWORD, JRELEASER_GPG_PASSPHRASE, JRELEASER_GPG_PUBLIC_KEY, JRELEASER_GPG_SECRET_KEY

Test plan

• ./gradlew clean build passes (compile + errorprone + tests + javadoc + spotless + license)
• ./gradlew javadoc passes with zero warnings
• ./gradlew publish produces staging artifacts in build/staging-deploy

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Note

Medium Risk
Medium risk because it changes artifact coordinates and the entire release/publishing pipeline (CI gating, signing, and deployment), which can break releases or downstream dependency resolution if misconfigured.

Overview
Switches distribution to Maven Central by changing published coordinates to io.consensys.protocols:discovery, generating sources/javadoc jars via Gradle, updating POM metadata, and replacing Cloudsmith publishing with a local staging repo plus jreleaser Maven Central deployment.

Modernizes build and CI by replacing grgit-based versioning with git-versioning, upgrading Error Prone + errorprone-checks, relaxing doclint to avoid missing-doc failures, and updating GitHub Actions to pinned SHAs with publish running only on tags using new JReleaser + GPG secrets. Minor hygiene: .factorypath ignored and a couple of Javadoc generic references escaped.

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