One maven { url "http://nexus..." } with allowInsecureProtocol = true lets anyone on the network swap the JARs your build runs, and nexusPassword=... in a committed gradle.properties lets anyone who reads the repository publish as you. This skill finds those and nine other Maven and Gradle build mistakes before you release, and tells you how to fix each one.

Your agent runs a scanner on your pom.xml files, Maven settings.xml files kept in the project, Gradle build scripts in Groovy and Kotlin DSL (build.gradle, build.gradle.kts, settings.gradle, applied *.gradle scripts), gradle.properties, the Gradle and Maven wrapper properties and gradle/libs.versions.toml. It reads POMs as XML with line numbers and fills in ${properties}, skips Groovy and Kotlin comments, knows which strings Gradle fills in ("$nexusPassword") and the safe forms (${env.NAME}, encrypted Maven passwords, credentials(PasswordCredentials::class), mavenLocal() with a content filter), and leaves your own SNAPSHOT version and sibling modules alone. It never runs Maven, Gradle or the wrapper. It returns BLOCK, REVIEW, or NOT FLAGGED, with the file, line, reason, and a safer approach. Secrets are never printed.

What it checks

BLOCK (fix before shipping)

• J01: http:// repositories, mirrors and publishing targets, allowInsecureProtocol, scripts applied from http://, and settings.xml overrides of Maven's maven-default-http-blocker mirror

• J02: passwords, tokens and signing keys written in build scripts, gradle.properties, POMs, settings.xml and repository or wrapper URLs (public Google Maps and Firebase keys are not reported)

• J03: the Gradle or Maven wrapper downloaded over http://

REVIEW (check before release)

• J11: dynamic versions: 1.+, latest.release, LATEST, RELEASE and version ranges

• J12: SNAPSHOT dependencies, plugins and parent POMs from other groups

• J13: mavenLocal() without a content filter

• J14: jcenter() and Bintray repository URLs

• J15: wrappers that download Gradle or Maven from a mirror or internal server without distributionSha256Sum

• J16: Maven plugins without a version

• J17: build scripts applied from an https:// URL

• J18: Maven repositories with checksumPolicy ignore

What's included

• The scanner (Python 3.9+, standard library only)

• A rules guide with the reason and safer approach for each rule

• A risky and a safe example project (a Maven service with the Maven wrapper, and a Gradle Kotlin DSL service with the wrapper, a version catalog and gradle.properties), and the real report the scanner produces on the risky one

Limits

It reads each file as written: parent POMs outside the scanned files, ~/.m2/settings.xml, ~/.gradle/gradle.properties, convention plugins in buildSrc or included builds, and values set on the command line or in CI are not followed, so a plugin version managed by a parent POM is trusted. .mvn/maven.config and Gradle dependency verification files are not read. NOT FLAGGED is not a guarantee.

Contents

One ZIP file with 23 files: SKILL.md, the scanner in scripts/ (5 Python files), references/rules.md (every rule with its reason and safer approach), and examples/ (15 example files plus report.md, the real scanner output on the risky example).

How to use: This is an agent skill: a folder with a SKILL.md file and Python scripts that an AI coding agent such as Claude Code, Cursor, or Codex CLI can run. Unzip it into your agent's skills folder (for Claude Code: ~/.claude/skills/), then ask your agent to check your project. The scripts also run on their own with Python 3.9 or newer, with nothing to install. They read your files only: no network access, and nothing is sent anywhere.