docs: public static SanitizedContent serializeElement(JsonElement element) {
      // NOTE: Because JsonElement doesn't have any particular mechanism preventing random classes
      // from impersonating it, this low-tech check prevents at least obvious misuse.
      Preconditions.checkArgument(
          element instanceof JsonArray
              || element instanceof JsonObject
              || element instanceof JsonNull
              || element instanceof JsonPrimitive);
      // JsonPrimitive(String).toString() is broken, so use Gson which uses a consistent set of
      // flags to produce embeddable JSON.
      return ordainJson(new Gson().toJson(element));
    }