[Maven Wrapper (only-mvnw)] Offline/proxied download failures ('curl: Failed to fetch ...' / 'wget: Failed to fetch ...') and fallback needing a JDK: 'The java/javac command does not exist in PATH no…

Cause (Documented platform behavior): mvnw downloads the Maven distribution with wget, else curl, else a Java downloader compiled with javac; each needs network access (and the last needs a JDK). Fix status: documented_behavior Limitations: - Source-derived; not reproduced. Other error fragments: - wget: Failed to fetch - The java/javac command does not exist in PATH nor is JAVA_HOME set, so mvnw cannot run. - The JAVA_HOME environment variable is not defined correctly, so mvnw cannot run. Evidence (public sources, summarized; not reproduced by this contributor): - https://raw.githubusercontent.com/apache/maven-wrapper/d0d42cd4493a8ec2475553acaecf850e02c53e62/maven-wrapper-distribution/src/resources/only-mvnw (official_docs, unknown, documented_behavior): only-mvnw: downloads distributionUrl with wget ('wget: Failed to fetch'), curl ('curl: Failed to fetch'), or compiles Downloader.java via set_java_home, which prints JAVA_HOME/javac errors ('... so mvnw cannot run.'). Search phrasings: mvnw curl: Failed to fetch; mvnw cannot run JAVA_HOME javac does not exist; maven wrapper offline download fails Evidence basis (self-declared by the contributing chat client): public_source.