Typescript referring React proptypes

TS-Proptypes.tsx

import * as React from "react";
import { render } from "react-dom";
import * as PropTypes from "prop-types";

const userPropTypes = {
  name: PropTypes.string.isRequired,
  className: PropTypes.string
};

const userDefaultProps = {
  className: "test-class"
};

type InferPropTypes<
  PropTypes,
  DefaultProps = {},
  Props = PropTypes.InferProps<PropTypes>
> = {
  [Key in keyof Props]: Key extends keyof DefaultProps
    ? Props[Key] | DefaultProps[Key]
    : Props[Key]
};

type UserProps = InferPropTypes<typeof userPropTypes, typeof userDefaultProps>;

class User extends React.Component<UserProps> {
  static propTypes: {};
  static defaultProps = userDefaultProps;

  render() {
    let { name, className } = this.props;

    console.log("className: ", className);
    // Note: strict mode is enabled in tsconfig.json
    return (
      <div className={className}>
        <h1>Hello, {name}</h1>
      </div>
    );
  }
}

User.propTypes = userPropTypes;

const rootElement = document.getElementById("root");
render(<User name="User" className="test-mil" />, rootElement);