[m2e-users] Multi-release jar project: howto automatically add additiona

["Thorsten Heit" <thorsten.heit@xxxxxx>]

Hi,

I'm working on some projects that actually target
Java 8, but are already prepared to be used in modular applications, i.e.
Java 11. I'm following the multirelease/single project runtime pattern
shown here:
https://github.com/apache/maven-compiler-plugin/blob/master/src/it/multirelease-patterns/singleproject-runtime/pom.xml


I have the following snippet in my parent pom:

<profile>
        <id>jdk9+</id>
        <activation>
           
    <jdk>[9,)</jdk>
        </activation>
        <build>
           
    <pluginManagement>
           
            <plugins>
           
               
    <plugin>
           
               
            <groupId>org.apache.maven.plugins</groupId>
           
               
            <artifactId>maven-compiler-plugin</artifactId>
           
               
            <version>3.8.1</version>
           
               
            <configuration>
           
               
               
    <release>8</release>
           
               
            </configuration>
           
               
    </plugin>
           
            </plugins>
           
    </pluginManagement>
        </build>
</profile>

<profile>
        <id>jdk11</id>
        <activation>
           
    <jdk>[11,)</jdk>
           
    <file>
           
            <exists>${basedir}/src/main/java11</exists>
           
    </file>
        </activation>
        <build>
           
    <pluginManagement>
           
            <plugins>
           
               
    <plugin>
           
               
            <groupId>org.apache.maven.plugins</groupId>
           
               
            <artifactId>maven-compiler-plugin</artifactId>
           
               
            <version>3.8.1</version>
           
               
            <executions>
           
               
               
    <execution>
           
               
               
            <id>jdk11</id>
           
               
               
            <goals>
           
               
               
               
    <goal>compile</goal>
           
               
               
            </goals>
           
               
               
            <configuration>
           
               
               
               
    <release>11</release>
           
               
               
               
    <compileSourceRoots>
           
               
               
               
            <compileSourceRoot>${project.basedir}/src/main/java11</compileSourceRoot>
           
               
               
               
    </compileSourceRoots>
           
               
               
               
    <multiReleaseOutput>true</multiReleaseOutput>
           
               
               
            </configuration>
           
               
               
    </execution>
           
               
            </executions>
           
               
    </plugin>

           
               
    <plugin>
           
               
            <groupId>org.apache.maven.plugins</groupId>
           
               
            <artifactId>maven-jar-plugin</artifactId>
           
               
            <version>3.2.0</version>
           
               
            <executions>
           
               
               
    <execution>
           
               
               
            <id>default-jar</id>
           
               
               
            <configuration>
           
               
               
               
    <archive>
           
               
               
               
            <manifestEntries>
           
               
               
               
               
    <Multi-Release>true</Multi-Release>
           
               
               
               
            </manifestEntries>
           
               
               
               
    </archive>
           
               
               
            </configuration>
           
               
               
    </execution>
           
               
            </executions>
           
               
    </plugin>
           
            </plugins>
           
    </pluginManagement>
        </build>
</profile>


Given the following structure in a depending project:

src/main/java
src/main/resources
src/main/java11
...

I'm able to compile it both with Java 8 or Java 11
as default JVM. So far, so good.

Question:
With Java 11 as default I have to manually add src/main/java11
as an additional source folder in Eclipse because it isn't discovered automatically
when I import such a project.
Is there a way to let m2e do this automatically for
me?


Regards

Thorsten