docs: public static Fault naturalize(Throwable ex) {
          while (ex instanceof InvocationTargetException || ex instanceof UndeclaredThrowableException) {
              ex = ex.getCause();
          }
          if (ex instanceof Fault) {
              return Fault.class.cast(ex);
          }
          return Fault.create(FaultCode.create(ex.getClass()), ex, ex.getMessage());
      }