title: React: get a list of a child's components
body: <p>I can get a list of a component's children and the props on each child:</p>
  <pre><code>React.Children.map(children, child =&gt; {
      if (React.isValidElement(child)) {
          console.log(child.props);
      }
  }
  </code></pre>
  <p>What if I wanted to grab the props off a component used within the child? So for example:</p>
  <pre><code>&lt;Table&gt;
    &lt;CustomColumnA /&gt;
    &lt;CustomColumnB /&gt;
  &lt;/Table&gt;
  
  const CustomColumnA = () =&gt; {
    return (
        &lt;Column
          prop1={true}
          prop2={&quot;hello&quot;} /&gt;
    );
  }
  </code></pre>
  <p>From within Table, I want to grab prop1 and prop2. Is this possible? the <code>Children.map</code> code above will print empty objects, because CustomColumnA is being called with no props. But the component it wraps has props and I need access to that.</p>
  <p>Thanks</p>