title: Read value of imported form component upon submit (without storing in state)
body: <p>I developed a component for ReactJS as to be used as a form item in conjunction with Antd's form. But, the <code>onFinish</code> callback function returns undefined for the value of my custom component. Probably, Antd's form is not being able to retrieve the value from my component. That does not happen when I am only using Antd components as form items.</p>
  <p>On the example below, <code>MultipleEntry</code> is the component I have developed. <code>MultipleEntry</code> has a nested TextArea component.</p>
  <pre><code>function Sandbox(props) {
  
      return (
          &lt;&gt;
              &lt;Form onFinish={(values) =&gt; console.log(values)}&gt;
                  &lt;Form.Item name={'myComponent'}  &gt;
                      &lt;MultipleEntry /&gt;
                  &lt;/Form.Item&gt;
                  &lt;Form.Item&gt;
                      &lt;Button type=&quot;primary&quot; htmlType=&quot;submit&quot;&gt;Submit&lt;/Button&gt;
                  &lt;/Form.Item&gt;
              &lt;/Form&gt;
  
          &lt;/&gt;
      );
  }
  
  
  function MultipleEntry(props) {
  
      const [value, setValue] = useState([]);
      
      const Split = string =&gt;
      {
          setValue(String(string).split(';'))
      }
  
      return (
          &lt;TextArea
              onChange={(e) =&gt; {Split(e.target.value)}}
          /&gt;
      );
  }
  
  </code></pre>
  <p>I thought about two alternatives here:</p>
  <ol>
  <li>Storing the values of <code>MultipleEntry</code> in its internal state.</li>
  <li>Storing the values of <code>MultipleEntry</code> on the parent component.</li>
  </ol>
  <p>But, I dont want to store the values anywhere on the client's state, since the data inside the <code>MultipleEntry</code> component would be too big and impactful for performance.</p>
  <p>How can I use Antd form's API to make it read the value of <code>MultipleEntry</code> as a form field, and populate the input parameter of <code>onFinish</code>?</p>