docs: public ServiceCall<Void> addGrammar(AddGrammarOptions addGrammarOptions) {
      Validator.notNull(addGrammarOptions, "addGrammarOptions cannot be null");
      String[] pathSegments = { "v1/customizations", "grammars" };
      String[] pathParameters = { addGrammarOptions.customizationId(), addGrammarOptions.grammarName() };
      RequestBuilder builder = RequestBuilder.post(RequestBuilder.constructHttpUrl(getEndPoint(), pathSegments,
          pathParameters));
      Map<String, String> sdkHeaders = SdkCommon.getSdkHeaders("speech_to_text", "v1", "addGrammar");
      for (Entry<String, String> header : sdkHeaders.entrySet()) {
        builder.header(header.getKey(), header.getValue());
      }
      builder.header("Accept", "application/json");
      builder.header("Content-Type", addGrammarOptions.contentType());
      if (addGrammarOptions.allowOverwrite() != null) {
        builder.query("allow_overwrite", String.valueOf(addGrammarOptions.allowOverwrite()));
      }
      builder.bodyContent(addGrammarOptions.contentType(), null, null, addGrammarOptions.grammarFile());
      return createServiceCall(builder.build(), ResponseConverterUtils.getVoid());
    }