Sources added by build-helper-maven-plugin are ignored

[machao81]

Hi,

I need some help with an issue in my project related to having multiple source folders.
I'm using the latest version of the rewrite-maven-plugin, configured like this:

<plugin>
          <groupId>org.openrewrite.maven</groupId>
          <artifactId>rewrite-maven-plugin</artifactId>
          <version>6.15.0</version>
		<configuration>
			<configLocation>./rewrite.yml</configLocation>
			<activeRecipes>
				<recipe>com.sylob.MigrationStruts</recipe>
			</activeRecipes>
		</configuration>
</plugin>

I’ve defined a simple recipe like this:

type: specs.openrewrite.org/v1beta/recipe
name: com.sylob.MigrationStruts
recipeList:
  - org.openrewrite.java.ChangeType:
      oldFullyQualifiedTypeName: org.apache.struts.action.ActionForward
      newFullyQualifiedTypeName: com.sylob.cochisemvc.model.CommandNextStep

My project has three source folders: niveau, socle, and specif, all of which contain Java code that I want to migrate using OpenRewrite.

My pom.xml looks like this:

<build>
    <finalName>Specif_******_Web</finalName>
    <sourceDirectory>specif</sourceDirectory>
[...]
   <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>build-helper-maven-plugin</artifactId>
        <executions>
          <execution>
            <goals>
              <goal>add-source</goal>
            </goals>
            <phase>generate-sources</phase>
            <configuration>
              <sources>
                <source>socle</source>
                <source>niveau</source>
                <source>specif</source>
              </sources>
            </configuration>
          </execution>
        </executions>
      </plugin>

The build-helper-maven-plugin is used to include multiple source folders instead of relying on the single sourceDirectory.

My issue is: Only the Java files in the sourceDirectory folder are processed by the rewrite-maven-plugin. The files in the other folders added by the build-helper-maven-plugin are ignored. However, Maven compiles all the Java files correctly and generates class files in the target directory.

Could someone explain how to make rewrite-maven-plugin process all source folders added with build-helper-maven-plugin?

Thanks in advance!

[timtebeek]

hi @machao81 ; thanks for the report! Linking some earlier work, where we explicitly only supported test sources:

• Rewrite sources added through build-helper-maven-plugin #755
• Add tests for multi source sets #888

It seems you're adding non-test sources here, is that correct? The fix might be quite straightforward in that case; help appreciated!

[machao81]

Hello @timtebeek,
Sorry for my late reply, I was on vacation.

Yes, these are 3 source code folders (not test sources).

   <source>socle</source>
   <source>niveau</source>
   <source>specif</source>

I would like the plugin to work on all the Java files contained in these three directories, and not only on the content of the folder specif.

Is there a workaround?

[timtebeek]

hi! There is no workaround, but the change should be fairly straightforward if you look at:

• https://github.com/openrewrite/rewrite-maven-plugin/pull/888/files

If you manage to get that in before Wednesday it'll go out with the next release.

[timtebeek]

@machao81 could you run ./mvn install on this branch and then try out the snapshot version on your local project ?

• Add support for multiple main source folders #1031

[machao81]

i will test it quickly. thanks

[machao81]

@timtebeek
Unfortunately, this change does not resolve my issue.
I’m not sure how I can help debug the plugin.
Would it be useful if I provided a minimal reproducible project?

[timtebeek]

That might help, but I can't promise to look at it any time soon; best bet is probably to checkout that branch locally and step through with mvnDebug and attaching a local debugger to see what's available in your case, or add a new unit test that better reflects your own project, and work from there. Hope that helps!

[machao81]

@timtebeek Hi Tim,

I ask Copilot to help me. I post the response of Copilot.

The real issue

mavenProject.getCompileSourceRoots() only contains the source directories that Maven knows about when the project model is built.
That means it includes your niveau but not the extra sources added later by the build-helper-maven-plugin.

Why?

The build-helper-maven-plugin runs in the generate-sources phase.

If you call getCompileSourceRoots() earlier (e.g. in validate or initialize), the plugin hasn’t run yet, so Maven hasn’t updated the compile source roots.

That’s why you only see niveau and not specif.

Solutions

1. Run your code after generate-sources

If you’re writing a custom Maven plugin (a Mojo), make sure it executes after the build-helper:add-source goal.
For example:

@Mojo (name = "list-sources", defaultPhase = LifecyclePhase.GENERATE_SOURCES)
public class ListSourcesMojo extends AbstractMojo {

    @Parameter(defaultValue = "${project}", readonly = true, required = true)
    private MavenProject project;

    public void execute() {
        for (String src : project.getCompileSourceRoots()) {
            getLog().info("Source dir: " + src);
        }
    }
}

Here, when your Mojo runs in generate-sources (or later, like compile), Maven has already applied the build-helper-maven-plugin changes, so project.getCompileSourceRoots() will include both niveau and specif.

2. Ensure build-helper runs before your plugin

If you can’t change the default phase, you can configure plugin execution order so that build-helper:add-source is invoked before your plugin.

3. Parse the POM directly

If for some reason you must run earlier (before generate-sources), you’d need to manually parse the section to extract what build-helper-maven-plugin would have added. But that’s brittle and not recommended.

✅ The recommended fix:

Run your code in generate-sources phase or later, so Maven has already updated getCompileSourceRoots() with all directories (niveau, specif, etc.).

[machao81]

So I tested the third solution because I’m not comfortable with the lifecycles.

i have replaced this code :

        // Some annotation processors output generated sources to the /target directory. These are added for parsing but
        // should be filtered out of the final SourceFile list.
        List<Path> generatedSourcePaths = listJavaSources(mavenProject.getBasedir().toPath().resolve(mavenProject.getBuild().getDirectory()));
        List<Path> mainJavaSources = new ArrayList<>(generatedSourcePaths);
        for (String p : mavenProject.getCompileSourceRoots()) {
            mainJavaSources.addAll(listJavaSources(mavenProject.getBasedir().toPath().resolve(p)));
        }

by something like that. The code below resolves my issue.

         // Some annotation processors output generated sources to the /target directory. These are added for parsing but
         // should be filtered out of the final SourceFile list.
		List<Path> generatedSourcePaths = listJavaSources(mavenProject.getBasedir().toPath().resolve(mavenProject.getBuild().getDirectory()));
		Path sourcePath = mavenProject.getBasedir().toPath().resolve(mavenProject.getBuild().getDirectory());
        logInfo(mavenProject, " -> Added build source directory: " + sourcePath.toString());
        List<Path> mainJavaSources = new ArrayList<>(listJavaSources(sourcePath));
      
        Plugin plugin = mavenProject.getPlugin("org.codehaus.mojo:build-helper-maven-plugin");
        if (plugin != null && !plugin.getExecutions().isEmpty()) {
        	logInfo(mavenProject, "Plugin build-helper-maven-plugin configuration found.");
            PluginExecution exec = plugin.getExecutions().get(0);
            Object rawConfig = exec.getConfiguration();

            if (rawConfig instanceof Xpp3Dom) {
                Xpp3Dom config = (Xpp3Dom) rawConfig;
                Xpp3Dom sources = config.getChild("sources");
                if (sources != null) {
                    for (Xpp3Dom src : sources.getChildren("source")) {
                        Path path = mavenProject.getBasedir().toPath().resolve(src.getValue());
                        logInfo(mavenProject, " -> Added source directory: " + path);
                        mainJavaSources.addAll(listJavaSources(path));
                    }
                }
            }
        }

[timtebeek]

Thanks for looking into it there; what command did you use to run the snapshot plugin? Because we already run after generate-sources:

rewrite-maven-plugin/src/main/java/org/openrewrite/maven/RewriteRunMojo.java

Lines 26 to 33 in c01aeb8

	* This variant of rewrite:run will fork the maven life cycle and can be run as a "stand-alone" goal. It will
	* execute the maven build up to the process-test-classes phase.
	*/
	@Execute(phase = LifecyclePhase.PROCESS_TEST_CLASSES)
	@Mojo(name = "run", requiresDependencyResolution = ResolutionScope.TEST, threadSafe = true,
	defaultPhase = LifecyclePhase.PROCESS_TEST_CLASSES)
	public class RewriteRunMojo extends AbstractRewriteRunMojo {
	}

The third option should then not be necessary. Perhaps it's easiest if you fork rewrite-maven-plugin and add a new unit test; that way we're looking at the same when trying to address this issue.