private boolean minimalSubfolders;

        registerExternalRoots(algorithm, true);

    }

    /**

     * Register all external source or non-source roots using {@link FileOwnerQuery#markExternalOwner}.

     * <p>

     * Only roots added by {@link #addPrincipalSourceRoot} and {@link #addNonSourceRoot}

     * are considered. They are registered if (and only if) they in fact fall

     * outside of the project directory, and of course only if the folders really

     * exist on disk. Currently it is not defined when this file existence check

     * is done (e.g. when this method is first called, or periodically) or whether

     * folders which are created subsequently will be registered, so project type

     * providers are encouraged to create all desired external roots before calling

     * this method.

     * </p>

     * <p>

     * If the actual value of the location changes (due to changes being

     * fired from the property evaluator), roots which were previously internal

     * and are now external will be registered, and roots which were previously

     * external and are now internal will be unregistered. The (un-)registration

     * will be done using the same algorithm as was used initially.

     * </p>

     * <p>

     * If a minimalSubfolders is true and an explicit include list is configured 

     * for a principal source root, only those subfolders which are included 

     * (or folders directly containing included files)

     * will be registered, otherwise the whole source root is registered.

     * Note that the source root, or an included subfolder, will

     * be registered even if it contains excluded files or folders beneath it.

     * </p>

     * <p>

     * Calling this method causes the helper object to hold strong references to the

     * current external roots, which helps a project satisfy the requirements of

     * {@link FileOwnerQuery#EXTERNAL_ALGORITHM_TRANSIENT}.

     * </p>

     * <p>

     * You may <em>not</em> call this method inside the project's constructor, as

     * it requires the actual project to exist and be registered in {@link ProjectManager}.

     * Typically you would use {@link org.openide.util.Mutex#postWriteRequest} to run it

     * later, if you were creating the helper in your constructor, since the project construction

     * normally occurs in read access.

     * </p>

     * @param algorithm an external root registration algorithm as per

     *                  {@link FileOwnerQuery#markExternalOwner}

     * @param minimalSubfolders controls how the roots having an explicit include list 

     * are registered. When true only those subfolders which are included 

     * (or folders directly containing included files) will be registered,

     * otherwise the whole source root is registered.

     * @throws IllegalArgumentException if the algorithm is unrecognized

     * @throws IllegalStateException if this method is called more than once on a

     *                               given <code>SourcesHelper</code> object

     * @since 1.26

     */

    public void registerExternalRoots (int algorithm, boolean minimalSubfolders) throws IllegalArgumentException, IllegalStateException {

        this.minimalSubfolders = minimalSubfolders;

    public void testMinimalSubfolders () throws Exception {

        scratch = TestUtil.makeScratchDir(this); // have our own setup

        maindir = scratch.createFolder("dir");

        projdir = maindir.createFolder("proj-dir");

        src1dir = maindir.createFolder("src1");

        // <editor-fold desc="create files in group #1">

        FileUtil.createData(src1dir, "com/sun/tools/javac/Main.java");

        FileUtil.createData(src1dir, "com/sun/tools/internal/ws/processor/model/java/JavaArrayType.java");

        FileUtil.createData(src1dir, "sun/tools/javac/Main.java");

        FileUtil.createData(src1dir, "sunw/io/Serializable.java");

        FileUtil.createData(src1dir, "java/lang/Byte.java");

        FileUtil.createData(src1dir, "java/text/resources/Messages.properties");

        FileUtil.createData(src1dir, "java/text/resources/Messages_zh.properties");

        FileUtil.createData(src1dir, "java/text/resources/Messages_zh_TW.properties");

        FileUtil.createData(src1dir, "java/text/resources/x_y/z.properties");

        // </editor-fold>

        // <editor-fold desc="other setup #1">

        h = ProjectGenerator.createProject(projdir, "test");

        project = ProjectManager.getDefault().findProject(projdir);

        EditableProperties p = h.getProperties(AntProjectHelper.PROJECT_PROPERTIES_PATH);

        p.setProperty("src1.dir", "../src1");

        // </editor-fold>

        // <editor-fold desc="includes & excludes">

        p.setProperty("src1.includes", "com/sun/tools/**");

        // </editor-fold>

        // <editor-fold desc="other setup #2">

        h.putProperties(AntProjectHelper.PROJECT_PROPERTIES_PATH, p);

        ProjectManager.getDefault().saveProject(project);

        //minimalSubfolders = true

        sh = new SourcesHelper(h, h.getStandardPropertyEvaluator());

        sh.addPrincipalSourceRoot("${src1.dir}", "${src1.includes}", "${src1.excludes}", "Sources #1", null, null);

        sh.addTypedSourceRoot("${src1.dir}", "${src1.includes}", "${src1.excludes}", "java", "Packages #1", null, null);

        sh.registerExternalRoots(FileOwnerQuery.EXTERNAL_ALGORITHM_TRANSIENT, true);

        Sources s = sh.createSources();

        SourceGroup[] groups = s.getSourceGroups("java");

        SourceGroup g1 = groups[0];

        assertEquals("Packages #1", g1.getDisplayName());

        assertNull(FileOwnerQuery.getOwner(src1dir));

        //minimalSubfolders = false

        sh = new SourcesHelper(h, h.getStandardPropertyEvaluator());

        sh.addPrincipalSourceRoot("${src1.dir}", "${src1.includes}", "${src1.excludes}", "Sources #1", null, null);

        sh.addTypedSourceRoot("${src1.dir}", "${src1.includes}", "${src1.excludes}", "java", "Packages #1", null, null);

        sh.registerExternalRoots(FileOwnerQuery.EXTERNAL_ALGORITHM_TRANSIENT, false);

        s = sh.createSources();

        groups = s.getSourceGroups("java");

        g1 = groups[0];

        assertEquals("Packages #1", g1.getDisplayName());

        assertEquals(project, FileOwnerQuery.getOwner(src1dir));

    }