title: Warning: findDOMNode is deprecated in StrictMode when using react-bootstrap Navbar
body: <p>I tried to use react-bootstrap's Navbar component in the typescript template and I found below warning in Chrome console.</p>
  
  <pre><code>index.js:1 Warning: findDOMNode is deprecated in StrictMode. findDOMNode was passed an instance of Transition which is inside StrictMode. Instead, add a ref directly to the element you want to reference.
      in div (created by Context.Consumer)
      in Transition (created by Collapse)
      in Collapse (created by Context.Consumer)
      in NavbarCollapse (at NavigationBar.tsx:10)
      in nav (created by Navbar)
      in Navbar (at NavigationBar.tsx:7)
      in NavigationBar (at App.tsx:8)
      in div (at App.tsx:7)
      in App (at src/index.tsx:10)
      in StrictMode (at src/index.tsx:9)
  </code></pre>
  
  <p>Below is the code</p>
  
  <pre><code>import React from 'react';
  import './NavigationBar.css';
  import { Navbar, Nav, NavDropdown } from 'react-bootstrap';
  
  function NavigationBar() {
      return (
          &lt;Navbar bg="light" expand="lg"&gt;
              &lt;Navbar.Brand href="#home"&gt;React-Bootstrap&lt;/Navbar.Brand&gt;
              &lt;Navbar.Toggle aria-controls="basic-navbar-nav" /&gt;
              &lt;Navbar.Collapse id="basic-navbar-nav"&gt;
                  &lt;Nav className="mr-auto"&gt;
                      &lt;Nav.Link href="#home"&gt;Home&lt;/Nav.Link&gt;
                      &lt;Nav.Link href="#link"&gt;Link&lt;/Nav.Link&gt;
                      &lt;NavDropdown title="Dropdown" id="basic-nav-dropdown"&gt;
                          &lt;NavDropdown.Item href="#action/3.1"&gt;Action&lt;/NavDropdown.Item&gt;
                          &lt;NavDropdown.Item href="#action/3.2"&gt;Another action&lt;/NavDropdown.Item&gt;
                          &lt;NavDropdown.Item href="#action/3.3"&gt;Something&lt;/NavDropdown.Item&gt;
                          &lt;NavDropdown.Divider /&gt;
                          &lt;NavDropdown.Item href="#action/3.4"&gt;Separated link&lt;/NavDropdown.Item&gt;
                      &lt;/NavDropdown&gt;
                  &lt;/Nav&gt;
              &lt;/Navbar.Collapse&gt;
          &lt;/Navbar&gt;);
  }
  
  export default NavigationBar;
  </code></pre>
  
  <p>Even the Navbar component's collapse function is working, what should I do to for warning message.</p>