void (@NotNull Collection<? super VirtualFile> container, @NotNull VirtualFile fromDirectory, @Nullable FileType fileType) { VfsUtilCore.visitChildrenRecursively(fromDirectory, new VirtualFileVisitor<Void>(VirtualFileVisitor.SKIP_ROOT) { @Override public boolean visitFile(@NotNull VirtualFile child) { if (!child.isDirectory() && (fileType == null || FileTypeRegistry.getInstance().isFileOfType(child, fileType))) { container.add(child); } return true; } }); }