}

        @Override
        public void visitFileTreeBackedByFile(File file, FileTreeInternal fileTree, FileSystemMirroringFileTree sourceTree) {
            cannotInferSourceRoots(fileTree);
        }

        @Override
        public void visitFileTree(File root, PatternSet patterns, FileTreeInternal fileTree) {

    override fun visitFileTree(root: File, patterns: PatternSet, fileTree: FileTreeInternal) =
        unsupportedFileTree(fileTree)

    override fun visitFileTreeBackedByFile(file: File, fileTree: FileTreeInternal, sourceTree: FileSystemMirroringFileTree) =
        unsupportedFileTree(fileTree)

    private
    fun unsupportedFileTree(fileTree: FileTreeInternal): Nothing =
        throw UnsupportedOperationException(

        setup:
        def mainSourceDirectory = Mock(Directory)
        def testSourceDirectory = Mock(Directory)
        def mainSourceFileTree = Mock(FileTreeInternal)
        def testSourceFileTree = Mock(FileTreeInternal)
        def delegate = Mock(TemplateOperation)
        def settings = createInitSettings( "my.lib")
        def factory = new TemplateFactory(settings, Language.JAVA, templateOperationFactory)

            }

            private void addTreeContents(FileTreeInternal fileTree) {
                // TODO - add some convenient way to visit the files of the tree without collecting them into a set
                files.addAll(fileTree.getFiles());
            }

            @Override
            public void visitFileTree(File root, PatternSet patterns, FileTreeInternal fileTree) {
                addTreeContents(fileTree);

    }

    def "dependencies are union of dependencies of source trees"() {
        def task1 = Stub(Task)
        def task2 = Stub(Task)
        def task3 = Stub(Task)
        def tree1 = Stub(FileTreeInternal)
        def tree2 = Stub(FileTreeInternal)

        given:
        tree1.visitDependencies(_) >> { TaskDependencyResolveContext context ->
            context.add(task1)
            context.add(task2)
        }

    }

    @Override
    public FileTreeInternal getAsFileTree() {
        return this;
    }

    @Override
    public FileTree plus(FileTree fileTree) {
        return new UnionFileTree(taskDependencyFactory, this, Cast.cast(FileTreeInternal.class, fileTree));
    }

    @Override
    public FileTree visit(Closure closure) {

        return ImmutableSet.of();
    }

    @Override
    protected void visitContents(FileCollectionStructureVisitor visitor) {
    }

    @Override
    public FileTreeInternal getAsFileTree() {
        return new EmptyFileTree(FileTreeInternal.DEFAULT_TREE_DISPLAY_NAME);
    }

    @Override
    public Optional<FileCollectionExecutionTimeValue> calculateExecutionTimeValue() {

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.gradle.api.internal.file.archive;

import org.gradle.api.internal.file.FileTreeInternal;
import org.gradle.api.internal.file.collections.FileSystemMirroringFileTree;
import org.gradle.api.internal.tasks.TaskDependencyContainer;
import org.gradle.api.internal.tasks.TaskDependencyResolveContext;

 */

package org.gradle.api.internal.file.collections

import org.gradle.api.Action
import org.gradle.api.file.FileVisitDetails
import org.gradle.api.file.FileVisitor
import org.gradle.api.internal.file.FileTreeInternal
import org.gradle.internal.nativeintegration.filesystem.FileSystem
import org.gradle.test.fixtures.file.TestNameTestDirectoryProvider
import org.gradle.util.UsesNativeServices
import org.junit.Rule

        return new DefaultConfigurableFileTree(fileResolver, listener, patternSetFactory, taskDependencyFactory, directoryFileTreeFactory);
    }

    @Override
    public FileTreeInternal treeOf(List<? extends FileTreeInternal> fileTrees) {
        if (fileTrees.isEmpty()) {
            return FileCollectionFactory.emptyTree();
        } else if (fileTrees.size() == 1) {
            return fileTrees.get(0);