Defect.version() throws when the Lints-Version manifest attribute is absent

Problem

Defect.version() throws an unhandled IllegalArgumentException when the Lints-Version manifest attribute is missing from the classpath — which happens when the library is used as a dependency, repackaged (shaded), or run from an IDE.

Root cause

src/main/java/org/eolang/lints/Defect.java:190-192:

public String version() {
    return new Manifests().read("Lints-Version");
}

jcabi-manifests Manifests.read(...) throws IllegalArgumentException ("Attribute 'Lints-Version' not found in MANIFEST.MF") when the attribute is absent. version() is delegated from DfContext.version() (src/main/java/org/eolang/lints/DfContext.java:54-56), so the risk is on the default path — the test DefectTest.returnsVersion passes only because Maven puts the manifest on the classpath.

Minimal example

// run with target/classes (no META-INF/MANIFEST.MF) or a shaded jar
new Defect.Default("x", Severity.ERROR, 1, "text").version(); // throws IllegalArgumentException

Expected behavior

version() should never throw: fall back to an empty string / "unknown" when the attribute is absent, and ideally cache the read once per JVM.

Related

• src/main/java/org/eolang/lints/DfContext.java:54-56 — the delegation path.

Start in src/main/java/org/eolang/lints/Defect.java around version() and review the delegation in src/main/java/org/eolang/lints/DfContext.java. Reproduce the missing-manifest case using target/classes or a shaded jar, then update the relevant test around DefectTest.returnsVersion. Done means Defect.version() returns the documented fallback instead of throwing when Lints-Version is absent.