private VirtualFile[] getChildren(VirtualFile file) {
      if (!isValid(file)) return null;
      if (file.isDirectory()) return file.getChildren();
      if (!descriptor.isChooseJarContents() || !FileElement.isArchive(file)) return null;
      String path = file.getPath() + JarFileSystem.JAR_SEPARATOR;
      VirtualFile jar = JarFileSystem.getInstance().findFileByPath(path);
      return jar == null ? VirtualFile.EMPTY_ARRAY : jar.getChildren();
    }
private VirtualFile[] getChildren(VirtualFile file)