public <S> S postGateway(final String path, final RequestBody requestBody, final Class<S> respType) throws IOException {
        Request.Builder requestBuilder = new Request.Builder().post(requestBody).url(gatewayEndpoint + path).addHeader(Constants.LOCAL_KEY, localKey);
        Response response = client.newCall(requestBuilder.build()).execute();
        String respBody = Objects.requireNonNull(response.body()).string();
        try {
            return GSON.fromJson(respBody, respType);
        } catch (Exception e) {
            return (S) respBody;
        }
    }
Send a post http request to shenyu gateway with custom requestBody.

@param <S>         type of response object
@param path        path
@param requestBody request Body
@param respType    response type passed to {@link Gson#fromJson(String, Class)}
@return response s
@throws IOException IO exception
shenyu-integrated-test/shenyu-integrated-test-common/src/main/java/org/apache/shenyu/integratedtest/common/helper/HttpHelper.java