apollo-openapi/src/main/java/com/ctrip/framework/apollo/openapi/client/service/AbstractOpenApiService.java/AbstractOpenApiService/execute
class AbstractOpenApiService:  private CloseableHttpResponse execute(HttpEntityEnclosingRequestBase requestBase, Object entity) throws IOException {
    requestBase.setEntity(new StringEntity(gson.toJson(entity), ContentType.APPLICATION_JSON));

    return execute(requestBase);
  }