@Nullable
  public static VirtualFile findRelative(String uri, @NotNull PsiFileSystemItem base) {
    String location = ExternalResourceManager.getInstance().getResourceLocation(uri, base.getProject());
    VirtualFile file = base.getVirtualFile();
    return VfsUtilCore.findRelativeFile(location, file != null && file.isValid() ? file : null);
  }
@Nullable
  public static VirtualFile findRelative(String uri, @NotNull PsiFileSystemItem base)