public static @Nullable XmlFile findNamespaceByLocation(@NotNull PsiFile base, @NotNull String nsLocation) {
    final String location = ExternalResourceManager.getInstance().getResourceLocation(nsLocation, base.getProject());
    return findXmlFile(base, location);
  }
public static @Nullable XmlFile findNamespaceByLocation(@NotNull PsiFile base, @NotNull String nsLocation)