code: @Override
    public final void attachNars(final File baseDir, final ArchiverManager archiverManager,
        final MavenProjectHelper projectHelper, final MavenProject project) throws MojoExecutionException {
      if (getNoArchDirectory(baseDir, project.getArtifactId(), project.getVersion()).exists()) {
        attachNar(archiverManager, projectHelper, project, NarConstants.NAR_NO_ARCH,
            getNoArchDirectory(baseDir, project.getArtifactId(), project.getVersion()), "*/**");
      }
  
      // list all directories in basedir, scan them for classifiers
      final String[] subDirs = baseDir.list();
      for (int i = 0; subDirs != null && i < subDirs.length; i++) {
        final String artifactIdVersion = project.getArtifactId() + "-" + project.getVersion();
  
        // skip entries not belonging to this project
        if (!subDirs[i].startsWith(artifactIdVersion)) {
          continue;
        }
  
        final String classifier = subDirs[i].substring(artifactIdVersion.length() + 1);
  
        // skip noarch here
        if (classifier.equals(NarConstants.NAR_NO_ARCH)) {
          continue;
        }
  
        final File dir = new File(baseDir, subDirs[i]);
        attachNar(archiverManager, projectHelper, project, classifier, dir, "*/**");
      }
    }
docs: /*
  (non-Javadoc)
  
  @see com.github.maven_nar.NarLayout#attachNars(java.io.File,
  org.apache.maven.project.MavenProjectHelper,
  org.apache.maven.project.MavenProject, com.github.maven_nar.NarInfo)