This POM simplifies the creation of multi-release jars.

Setup

Make this your parent POM:

    <parent>
        <groupId>com.meterware</groupId>
        <artifactId>multirelease-parent</artifactId>
        <version>1.2.0</version>
    </parent>

You must have a toolchains.xml defined in your maven configuration directory (~/.m2/toolchains.xml on OS X and Linux)

Code for the main jar (JDK 1.7-1.8) goes under src/main/java as usual.

Code additions for later JDKs, along with module-info.jar go under src/main/java9, src/main/java10 or src/main/java11

Unit Testing

mvn clean test will use the current JDK (the one running Maven)to run unit tests, including the appropriate additional directories.

Building the MR JAR

mvn -Dmulti_release clean install will create the multi-release JAR, using toolchains to select the appropriate compiler for each jar. This will automatically happen when using the release plugin.

Notes:

This parent POM inherits from org.sonatype.oss:oss-parent:9 and brings with it all associated definitions.

By default, builds with this parent will use JDK 1.7 to build the main jar. You can change that by adding

<base.java.version>1.8</base.java.version>

to your <properties> section.