title: Should Reacts `propTypes` and `defaultProps` be used in conjunction with Flowtype, or is Flowtype comprehensive enough?
body: <p>Thinking of a simple example such as:</p>
  
  <pre><code>class CommentAreaComponent extends React.Component {
  static propTypes = {
      id: PropTypes.string.isRequired,
      loading: PropTypes.bool,
  };
  
  static defaultProps = {
      loading: false,
  };
  </code></pre>
  
  <p>In the constructor I can define something like this to achieve (I think) the same thing:</p>
  
  <pre><code>class MyComponent extends React.Component {
      constructor({
          loading = false,
      }:{ 
          id:string, 
          loading?:boolean 
      }) {
          super(arguments[0]);
      }
  }
  </code></pre>
  
  <p>The second example is using only Flowtype. Does using Reacts PropTypes and DefaultProps offer an advantage? Or can I drop them completely when using FlowType?</p>