title: Refs are always null inside modal component
body: <p>All refs created inside the reactstrap modal component are null inside compoenentDIDMount no matter how they are created</p>
  
  <p>This is related to react-dom version 16.8.6.  I have tried assigning ref directly, using react.createRef(), and callbacks.</p>
  
  <pre><code>import { Modal, Form } from 'reactstrap'
  
  class QuickBidModal extends React.Component {
      constructor(props) {
          super(props);
          this.state = {
            isOpen: false,
          };
          this.input1 = React.createRef();
      }
  
  componentDidMount(){
    console.log(this.input1) //Always returns current as null
  }
  
  render(){
   &lt;Modal&gt;
    &lt;Form&gt;
    &lt;div className="input" ref={this.input1} /&gt;
    &lt;/Form&gt;
  
   &lt;/Modal&gt;
  }
  </code></pre>
  
  <p>I expect this.input1 to be of class input on the current property.  However, it only returns null.  If I create the div element OUTSIDE of the Modal component, then the ref works properly.</p>