docs: private boolean hasToBuilderMethod(
        DeclaredType builder,
        boolean isExtensible,
        Iterable<ExecutableElement> methods) {
      for (ExecutableElement method : methods) {
        if (isToBuilderMethod(builder, method)) {
          if (!isExtensible) {
            messager.printMessage(ERROR,
                "No accessible no-args Builder constructor available to implement toBuilder",
                method);
          }
          return true;
        }
      }
      return false;
    }