docs: public ServiceCall<Void> addWords(AddWordsOptions addWordsOptions) {
      Validator.notNull(addWordsOptions, "addWordsOptions cannot be null");
      String[] pathSegments = { "v1/customizations", "words" };
      String[] pathParameters = { addWordsOptions.customizationId() };
      RequestBuilder builder = RequestBuilder.post(RequestBuilder.constructHttpUrl(getEndPoint(), pathSegments,
          pathParameters));
      Map<String, String> sdkHeaders = SdkCommon.getSdkHeaders("text_to_speech", "v1", "addWords");
      for (Entry<String, String> header : sdkHeaders.entrySet()) {
        builder.header(header.getKey(), header.getValue());
      }
      builder.header("Accept", "application/json");
      final JsonObject contentJson = new JsonObject();
      contentJson.add("words", GsonSingleton.getGson().toJsonTree(addWordsOptions.words()));
      builder.bodyJson(contentJson);
      return createServiceCall(builder.build(), ResponseConverterUtils.getVoid());
    }