title: How to set multi line header in react native?
body: <p>I try to add a multi line title to my header like this:</p>
  
  <pre><code>    Title
    Subtitle
  </code></pre>
  
  <p>I tried the code below. It doesn't work, I got an error "title must be string or null"</p>
  
  <pre><code> static navigationOptions = ({ navigation }) =&gt; {
      return {
      title: 
      &lt;View&gt;
      &lt;Text&gt;{navigation.getParam('client') }&lt;/Text&gt;
      &lt;Text&gt;{navigation.getParam('ref') }&lt;/Text&gt;
      &lt;/View&gt;,
  </code></pre>
  
  <p>I followed this issue on github <a href="https://github.com/react-navigation/react-navigation/issues/2430" rel="nofollow noreferrer">https://github.com/react-navigation/react-navigation/issues/2430</a></p>