Maven wrapper

With version 4.2.0, the maven wrapper was introduced.

The Maven Wrapper is an easy way to ensure a user of your Maven build has everything necessary to run your Maven build.

The official documentation is here.

Normally you instruct users to install a specific version of Apache Maven, put it on the PATH and then run the mvn command like the following:

mvn clean install

But now, with a Maven Wrapper setup, you can instruct users to run wrapper scripts:

./mvnw clean install

or on Windows

mvnw.cmd clean install

A normal Maven build will be executed with the one important change that if the user doesn't have the necessary version of Maven specified in .mvn/wrapper/maven-wrapper.properties it will be downloaded for the user first, installed and then used.

Subsequent uses of mvn/mvnw.cmd use the previously downloaded, specific version as needed.