[FIXED] M2E and having maven generated source folders as eclipse source folders

Issue

I have a maven project in eclipse and have maven goals that run annotation processors to generate code. The output folder for this code is target/generated-sources/apt.

In order for Eclipse to see this generated code I need to add target/generated-sources/apt as a source folder to the Eclipse project.

However, this causes there to be an error of type "Maven Configuration Problem" saying

Project configuration is not up-to-date with pom.xml. Run project configuration update

I think I understand why this is the case as Eclipse has a different set of source folders to Maven's set. But I need this different set, as I need Eclipse to be able to see the generated source folders...

When doing a pure Maven built, these source folders will be included in the build, by Maven.

BTW, I have upgraded to the official Eclipse release of the Maven Eclipse plugin, m2e 1.0 - what used to be m2eclipse. I'd like to see if I can find a work around/solution to this with the m2e plugin before I have to go back to the old m2eclipse version.

Solution

You need to attach the source directory with the build-helper-plugin.

Like so:

 <plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>build-helper-maven-plugin</artifactId>
    <executions>
        <execution>
            <id>add-source</id>
            <phase>generate-sources</phase>
            <goals>
                <goal>add-source</goal>
            </goals>
            <configuration>
                <sources>
                    <source>${project.build.directory}/generated-sources/java/</source>
                </sources>
            </configuration>
        </execution>
    </executions>
 </plugin>

You will also need to:

• Install the "Apt M2E Connector" from the Eclipse Marketplace. To do so click the error in the Overview tab of your pom.xml and select "Discover".
• Ensure there are no plugin execution filters for the build-helper-maven-plugin (see https://www.eclipse.org/m2e/documentation/m2e-execution-not-covered.html)

Answered By - Michael-O
Answer Checked By - Pedro (JavaFixing Volunteer)