public boolean contains(File file) {
        for (FileCollection collection : getSourceCollections()) {
            if (collection.contains(file)) {
                return true;
            }
        }
        return false;
    }

    @Override
    public boolean isEmpty() {
        for (FileCollection collection : getSourceCollections()) {
            if (!collection.isEmpty()) {
                return false;

        super(taskDependencyFactory);
    }

    public CompositeFileTree() {
        super();
    }

    @Override
    protected List<? extends FileTreeInternal> getSourceCollections() {
        return Cast.uncheckedNonnullCast(super.getSourceCollections());
    }

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