if (!addLookupBefore) {

            for (FileSystem f : result.allInstances()) {

                if (Boolean.TRUE.equals(f.getRoot().getAttribute("fallback"))) { // NOI18N

                    l.add(f);

                }

            }

        }

    public void testJustAttributes() throws SAXException, IOException {

        BinaryCacheManager m = new BinaryCacheManager();

        List<URL> urls = new ArrayList<URL>(Arrays.asList(BinaryCacheManagerTest.class.getResource("data/attribsonly.xml")));

        FileSystem fs = store(m, urls);

        assertEquals(Boolean.TRUE, fs.getRoot().getAttribute("myAttr"));

    }

/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

 *

 * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.

 *

 * The contents of this file are subject to the terms of either the GNU

 * General Public License Version 2 only ("GPL") or the Common

 * Development and Distribution License("CDDL") (collectively, the

 * "License"). You may not use this file except in compliance with the

 * License. You can obtain a copy of the License at

 * http://www.netbeans.org/cddl-gplv2.html

 * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the

 * specific language governing permissions and limitations under the

 * License.  When distributing the software, include this License Header

 * Notice in each file and include the License file at

 * nbbuild/licenses/CDDL-GPL-2-CP.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the GPL Version 2 section of the License file that

 * accompanied this code. If applicable, add the following below the

 * License Header, with the fields enclosed by brackets [] replaced by

 * your own identifying information:

 * "Portions Copyrighted [year] [name of copyright owner]"

 *

 * Contributor(s):

 *

 * The Original Software is NetBeans. The Initial Developer of the Original

 * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun

 * Microsystems, Inc. All Rights Reserved.

 *

 * If you wish your version of this file to be governed by only the CDDL

 * or only the GPL Version 2, indicate your decision by adding

 * "[Contributor] elects to include this software in this distribution

 * under the [CDDL or GPL Version 2] license." If you do not indicate a

 * single choice of license, a recipient has the option to distribute

 * your version of this file under either the CDDL, the GPL Version 2 or

 * to extend the choice of license to its licensees as provided above.

 * However, if you add GPL Version 2 code and therefore, elected the GPL

 * Version 2 license, then the option applies only if the new code is

 * made subject to such option by the copyright holder.

 */

package org.netbeans.core.startup.layers;

import java.io.File;

import java.io.IOException;

import java.io.OutputStream;

import java.util.Arrays;

import java.util.Iterator;

import junit.framework.Test;

import org.netbeans.core.startup.MainLookup;

import org.netbeans.junit.NbModuleSuite;

import org.netbeans.junit.NbTestCase;

import org.openide.filesystems.FileObject;

import org.openide.filesystems.FileSystem;

import org.openide.filesystems.FileUtil;

import org.openide.filesystems.LocalFileSystem;

import org.openide.util.Lookup;

import org.openide.util.lookup.InstanceContent;

/** Test layering of filesystems installed via lookup.

 *

 * @author Jaroslav Tulach

 */

public class DynamicSFSFallbackTest extends NbTestCase

implements InstanceContent.Convertor<FileSystem,FileSystem> {

    FileSystem fs1;

    FileSystem fs2;

    public DynamicSFSFallbackTest(String testName) {

        super(testName);

    }

    public static Test suite() {

        return NbModuleSuite.create(

            NbModuleSuite.emptyConfiguration().

            addTest(DynamicSFSFallbackTest.class).

            clusters("org-netbeans-core-ui.*")

        );

    }

    @Override

    protected void setUp() throws Exception {

    }

    @Override

    protected void tearDown() throws Exception {

        super.tearDown();

        MainLookup.unregister(fs1, this);

        MainLookup.unregister(fs2, this);

    }

    public void testDynamicSystemsCanAlsoBeBehindLayers() throws Exception {

        FileObject global = FileUtil.getConfigFile("Toolbars/Standard.xml");

        assertNotNull("File Object installed: " + global, global);

        if (global.asText().indexOf("<Toolbar name=") == -1) {

            fail("Expecting toolbar definition: " + global.asText());

        }

        final LocalFileSystem lfs1 = new LocalFileSystem();

        File dir1 = new File(getWorkDir(), "dir1");

        dir1.mkdirs();

        lfs1.setRootDirectory(dir1);

        lfs1.getRoot().setAttribute("fallback", Boolean.TRUE);

        assertEquals("Position attribute is there", Boolean.TRUE, lfs1.getRoot().getAttribute("fallback"));

        fs1 = lfs1;

        fs2 = FileUtil.createMemoryFileSystem();

        FileObject fo1 = FileUtil.createData(fs1.getRoot(), global.getPath());

        fo1.setAttribute("one", 1);

        write(fo1, "fileone");

        FileObject fo11 = FileUtil.createData(fs1.getRoot(), "test-fs-is-there.txt");

        write(fo11, "hereIam");

        MainLookup.register(fs1, this);

        MainLookup.register(fs2, this);

        Iterator<? extends FileSystem> it = Lookup.getDefault().lookupAll(FileSystem.class).iterator();

        assertTrue("At least One", it.hasNext());

        assertEquals("first is fs1", fs1, it.next());

        assertTrue("At least two ", it.hasNext());

        assertEquals("first is fs2", fs2, it.next());

        if (global.asText().indexOf("<Toolbar name=") == -1) {

            fail("Still Expecting toolbar definition: " + global.asText());

        }

        assertTrue("Still valid", global.isValid());

        FileObject fo = FileUtil.getConfigFile("test-fs-is-there.txt");

        assertNotNull("File found: " + Arrays.toString(FileUtil.getConfigRoot().getChildren()), fo);

        assertEquals("Text is correct", "hereIam", fo.asText());

    }

    private static void write(FileObject fo, String txt) throws IOException {

        OutputStream os = fo.getOutputStream();

        os.write(txt.getBytes());

        os.close();

    }

    public FileSystem convert(FileSystem obj) {

        return obj;

    }

    public Class<? extends FileSystem> type(FileSystem obj) {

        return obj.getClass();

    }

    public String id(FileSystem obj) {

        return obj.getDisplayName();

    }

    public String displayName(FileSystem obj) {

        return obj.getDisplayName();

    }

}

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE filesystem PUBLIC "-//NetBeans//DTD Filesystem 1.1//EN" "http://www.netbeans.org/dtds/filesystem-1_1.dtd">

<filesystem>

    <attr name="myAttr" boolvalue="true"/>

</filesystem>

        urls.add(0, FoDFileSystem.class.getResource("common.xml")); // NOI18N

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE filesystem PUBLIC "-//NetBeans//DTD Filesystem 1.2//EN" "http://www.netbeans.org/dtds/filesystem-1_2.dtd">

<filesystem>

    <attr name="fallback" boolvalue="true"/>

</filesystem>

      <p>

          Since version 7.23 you can use <api name="SystemFileSystem.fallback" group="property"

          type="export" category="stable">

              By returning <code>Boolean.TRUE</code> from call

                    to <code>fs.getRoot().getAttribute("fallback")</code>

                    you can place your filesystem behind all layers provided

                    by standard modules and form a kind of <q>fallback</q>

         </api>

      </p>

            for (FileSystem f : ALL.allInstances()) {

                if (Boolean.TRUE.equals(f.getRoot().getAttribute("fallback"))) { // NOI18N

                    continue;

                }

                arr.add(f);

            }

/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

 *

 * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.

 *

 * The contents of this file are subject to the terms of either the GNU

 * General Public License Version 2 only ("GPL") or the Common

 * Development and Distribution License("CDDL") (collectively, the

 * "License"). You may not use this file except in compliance with the

 * License. You can obtain a copy of the License at

 * http://www.netbeans.org/cddl-gplv2.html

 * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the

 * specific language governing permissions and limitations under the

 * License.  When distributing the software, include this License Header

 * Notice in each file and include the License file at

 * nbbuild/licenses/CDDL-GPL-2-CP.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the GPL Version 2 section of the License file that

 * accompanied this code. If applicable, add the following below the

 * License Header, with the fields enclosed by brackets [] replaced by

 * your own identifying information:

 * "Portions Copyrighted [year] [name of copyright owner]"

 *

 * Contributor(s):

 *

 * The Original Software is NetBeans. The Initial Developer of the Original

 * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun

 * Microsystems, Inc. All Rights Reserved.

 *

 * If you wish your version of this file to be governed by only the CDDL

 * or only the GPL Version 2, indicate your decision by adding

 * "[Contributor] elects to include this software in this distribution

 * under the [CDDL or GPL Version 2] license." If you do not indicate a

 * single choice of license, a recipient has the option to distribute

 * your version of this file under either the CDDL, the GPL Version 2 or

 * to extend the choice of license to its licensees as provided above.

 * However, if you add GPL Version 2 code and therefore, elected the GPL

 * Version 2 license, then the option applies only if the new code is

 * made subject to such option by the copyright holder.

 */

package org.openide.filesystems;

import java.io.File;

import java.io.IOException;

import java.io.OutputStream;

import java.util.Arrays;

import org.netbeans.junit.MockServices;

import org.netbeans.junit.NbTestCase;

import org.openide.util.lookup.InstanceContent;

/** Test layering of filesystems installed via lookup.

 *

 * @author Jaroslav Tulach

 */

public class DynamicSFSFallbackTest extends NbTestCase

implements InstanceContent.Convertor<FileSystem,FileSystem> {

    public DynamicSFSFallbackTest(String testName) {

        super(testName);

    }

    @Override

    protected void setUp() throws Exception {

        MyFS1.dir = new File(getWorkDir(), "dir1");

        MyFS2.dir = new File(getWorkDir(), "dir2");

        MockServices.setServices(MyFS1.class, MyFS2.class);

    }

    @Override

    protected void tearDown() throws Exception {

        super.tearDown();

    }

    public static final class MyFS1 extends LocalFileSystem {

        static File dir;

        public MyFS1() throws Exception {

            dir.mkdirs();

            setRootDirectory(dir);

            getRoot().setAttribute("fallback", Boolean.TRUE);

            FileObject fo1 = FileUtil.createData(getRoot(), "test/data.txt");

            fo1.setAttribute("one", 1);

            write(fo1, "fileone");

            FileObject fo11 = FileUtil.createData(getRoot(), "test-fs-is-there.txt");

            write(fo11, "hereIam");

        }

    }

    public static final class MyFS2 extends LocalFileSystem {

        static File dir;

        public MyFS2() throws Exception {

            dir.mkdirs();

            setRootDirectory(dir);

            FileObject fo1 = FileUtil.createData(getRoot(), "test/data.txt");

            fo1.setAttribute("two", 1);

            write(fo1, "two");

        }

    }

    public void testDynamicSystemsCanAlsoBeBehindLayers() throws Exception {

        FileObject global = FileUtil.getConfigFile("test/data.txt");

        assertEquals("Second file system takes preceedence", "two", global.asText());

        assertTrue("Still valid", global.isValid());

        FileObject fo = FileUtil.getConfigFile("test-fs-is-there.txt");

        assertNotNull("File found: " + Arrays.toString(FileUtil.getConfigRoot().getChildren()), fo);

        assertEquals("Text is correct", "hereIam", fo.asText());

    }

    private static void write(FileObject fo, String txt) throws IOException {

        OutputStream os = fo.getOutputStream();

        os.write(txt.getBytes());

        os.close();

    }

    public FileSystem convert(FileSystem obj) {

        return obj;

    }

    public Class<? extends FileSystem> type(FileSystem obj) {

        return obj.getClass();

    }

    public String id(FileSystem obj) {

        return obj.getDisplayName();

    }

    public String displayName(FileSystem obj) {

        return obj.getDisplayName();

    }

}