title: How do I specify a default value in vaadin-combo-box?
body: <p>I have created a combo box component using lit and vaadin-combo-box.
  I was able to create the combo box without any problems, but I don't know how to set the default value.
  How can I set the default value to &quot;Label 1&quot; before selecting it?</p>
  <pre><code>import {customElement} from 'lit/decorators.js';
  import {html, LitElement} from 'lit';
  
  const items = [
    {'label': 'Label 1', 'value': 'label1'},
    {'label': 'Label 2', 'value': 'label2'},
  ];
  
  @customElement('my-element')
  export class MyElement extends LitElement {
    render() {
      return html`
        &lt;vaadin-combo-box
            label=&quot;combo box&quot;
            .items=&quot;${items}&quot;
            required
        &gt;
        &lt;/vaadin-combo-box&gt;
      `;
    }
  }
  </code></pre>