@NotNull
  public static Collection<VirtualFile> getSourceRoots(@NotNull PsiElement foothold) {
    final Module module = ModuleUtilCore.findModuleForPsiElement(foothold);
    if (module != null) {
      return getSourceRoots(module);
    }
    return Collections.emptyList();
  }
@NotNull
  public static Collection<VirtualFile> getSourceRoots(@NotNull PsiElement foothold)