name: detect-java-version
description: Detect a Maven/Gradle project's REAL current Java level (by its declared bytecode target, not the build toolchain) and dispatch to the matching one-LTS bump hop (8->11, 11->17, 17->21, 21->25). Use as the entry point: it decides the hop and whether the project should be bumped at all.
Bump a project one Java LTS: two steps: DETECT, then HOP
A project's build toolchain (the JDK Gradle/Maven builds with) is NOT its bytecode target (the Java
version it emits). Many libraries deliberately build with a new JDK but pin old bytecode for consumer reach
(OpenTelemetry instrumentation, Gradle plugins, SDKs). Dispatching on the toolchain mislabels these and tries
an impossible/harmful bump. So always detect the real level first.
Step 1: detect the real current level + bumpability
detect_java_version.sh <repo> <sha> -> JSON. It reads, across ALL modules, the declared bytecode target
(precedence: options.release / <maven.compiler.release> > source/targetCompatibility / <source> /
jvmTarget > the toolchain languageVersion), and reports:
detected, the MIN bytecode target across modules (the true current Java level).low_target, TRUE if a bytecode target is pinned BELOW the toolchain, OR modules target different levels
(multi-target), OR a java-gradle-plugin is applied. These are deliberate-low-target projects.bumpable, TRUE only if a clean single target below the latest LTS AND not low_target.hop_to, the next LTS above detected.
Step 2: dispatch
bumpable: false -> NOT_A_BUMP (record + stop). Bumping its bytecode would regress its consumers; it
is not a migration target. Do NOT score it as a failed bump.- else -> run the matching per-hop skill for
detected's LTS bracket: 8->11, 11->17, 17->21, or 21->25
(build JDKs are the LTS rungs; a non-LTS detected level brackets down, e.g. 14 -> the 11->17 hop).
The orchestrator run_repo.sh <repo> <sha> <slug> does both: detect -> NOT_A_BUMP or dispatch.
