static void propagateFirstIOException(Throwable throwable) throws IOException {
    while (throwable != null) {
      if (throwable instanceof IOException) {
        throw (IOException) throwable;
      }
      throwable = throwable.getCause();
    }
  }
@deprecated Use the {@link RibbonClient#create()}
ribbon/src/main/java/feign/ribbon/RibbonClient.java