Phalanx CI Fixer v2 — Java Testbed

Controlled failures in Java so the v2 agent can diagnose, fix, and close PRs end-to-end. Mirror of the Python / TS / JS testbeds but for the Java scorecard row.

• 5 languages × 4 failure classes = 20 scorecard cells. This repo covers the 4 Java cells.
• Each failures/*.patch introduces one class of CI failure when applied to main.
• CI runs Checkstyle (Lint job) and mvn verify with JaCoCo 80% gate (Test + Coverage job).

Intentional failure patches

Patch	Cell	What it breaks
01-lint.patch	lint	Checkstyle LineLength violation (>100 cols) in MathOps.java
02-test-assertion.patch	test_fail	multiply returns a + b instead of a * b
03-flake-sleep.patch	flake	Thread.sleep((long)(Math.random() * 3000)) inside a 2s Surefire timeout
04-coverage-drop.patch	coverage	Adds two untested helpers → JaCoCo line coverage under 80%

Running locally

mvn -B checkstyle:check   # lint
mvn -B verify             # tests + JaCoCo coverage gate

JDK 21 required. Maven handles everything else.