code: public static void checkUpdate(DatasetDescriptor existing,
                                   DatasetDescriptor updated) {
      checkNotChanged("location", existing.getLocation(), updated.getLocation());
      checkCompatible(existing, updated);
    }
docs: Checks that the {@code existing} {@link DatasetDescriptor} can be replaced
  by {@code updated}.
  
  @param existing the current {@code DatasetDescriptor} for a dataset
  @param updated a new {@code DatasetDescriptor} for the same dataset