code: public static Datatype.Builder from(Datatype value) {
      if (value instanceof Rebuildable) {
        return ((Rebuildable) value).toBuilder();
      } else {
        return new Datatype.Builder().mergeFrom(value);
      }
    }
docs: Creates a new builder using {@code value} as a template.
  
  <p>If {@code value} is a partial, the builder will return more partials.