[arturobernalg]

The download block in only-mvnw tries wget, then curl, then falls back to Java, but had no final else. When none of the three are available, the if/elif chain silently falls through instead of failing, and the script only reports a confusing "failed to unzip" error from the later unzip step, which can never find a distribution archive that was never downloaded.

Adds the missing else branch to fail immediately with a clear message, and a guard right after the download block that fails if the distribution file does not exist, before any further processing. Fixes #441.

What

Fixes #441: mvnw (generated with distributionType=only-script) silently continues when none of wget, curl or a JDK are available to download the Maven distribution, instead of failing with a clear message.

How

• Adds a final else to the wget/curl/Java download dispatch in only-mvnw, calling die with a message naming the three possible download mechanisms.
• Adds a guard right after the download block that fails with a clear message if the distribution archive was not actually downloaded, before the script moves on to checksum validation and unzip.
• Same approach as the previously proposed fix in Fail when only-script mvnw has no download tool #441 #443 (closed by the stale-bot for inactivity, not because it was wrong).

Tests

• Reproduced the bug first: ran only-mvnw with PATH stripped of wget/curl/java/javac and JAVA_HOME unset against a real maven-wrapper.properties. Before the fix it printed the JAVA_HOME warning and then failed later with a confusing unzip: cannot find or open ... failed to unzip (exit 1). After the fix it fails immediately with No download mechanism available: install wget or curl, or make a JDK available on PATH / via JAVA_HOME (exit 1).
• Ran the fixed script with a normal PATH (curl available): downloads and runs Maven 3.9.9 successfully, no regression.
• sh -n only-mvnw: syntax OK.

---

To make clear that you license your contribution under
the Apache License Version 2.0, January 2004
check one of the following:

• I hereby declare this contribution to be licensed under the Apache License Version 2.0, January 2004
• I hereby declare that I have filed an Apache Individual Contributor License Agreement.