title: Vuetify Combobox add new item as object instead of string
body: <p>I am building a new/edit item form using <code>Vuetify(v2.6.3)</code>. My form has multiple combobox's that pull their items from a backend API as objects. I would like to be able to add new items, which the combobox is able to do. However, when I add a new item it's added as a string. Is there a way to add that new item as an object instead?</p>
  <p>I only need the new object to have a <code>name</code> key in order to send it to the API to be created</p>
  <p>Desired <code>New</code> item from <code>v-combobox</code>:</p>
  <pre class="lang-js prettyprint-override"><code>{
    name: 'New Item',
  }
  </code></pre>
  <p>Simplified list of items returned from API and available as combobox choices:</p>
  <pre class="lang-js prettyprint-override"><code>[
    { 
      id: 1, 
      name: 'Item 1', 
      createdAt: '2020-01-01', 
      updatedAt: '2020-01-01' 
    },
    { 
      id: 2, 
      name: 'Item 2', 
      createdAt: '2020-01-01', 
      updatedAt: '2020-01-01' 
    },
    { 
      id: 3, 
      name: 'Item 3', 
      createdAt: '2020-01-01', 
      updatedAt: '2020-01-01' 
    }
  ]
  </code></pre>
  <p>Here is a simplified version of my Form:</p>
  <pre class="lang-html prettyprint-override"><code>&lt;template&gt;
    &lt;v-card&gt;
      &lt;v-card-title&gt;
        &lt;span class=&quot;text-h5&quot;&gt;Edit Item&lt;/span&gt;
      &lt;/v-card-title&gt;
      &lt;v-card-text&gt;
        &lt;v-container&gt;
          &lt;v-row&gt;
            &lt;v-col&gt;
              &lt;v-combobox
                v-model=&quot;item&quot;
                :items=&quot;items&quot;
                item-text=&quot;name&quot;
                item-value=&quot;id&quot;
                label=&quot;ComboBox&quot;
                return-object
              &gt;&lt;/v-combobox&gt;
            &lt;/v-col&gt;
          &lt;/v-row&gt;
        &lt;/v-container&gt;
      &lt;/v-card-text&gt;
    &lt;/v-card&gt;
  &lt;/template&gt;
  &lt;script&gt;
  export default {
    name: 'TestForm',
    data() {
      return {
        item: null,
        items: [
          {
            id: 1,
            name: 'Item 1',
            createdAt: '2020-01-01',
            updatedAt: '2020-01-01',
          },
          {
            id: 2,
            name: 'Item 2',
            createdAt: '2020-01-01',
            updatedAt: '2020-01-01',
          },
          {
            id: 3,
            name: 'Item 3',
            createdAt: '2020-01-01',
            updatedAt: '2020-01-01',
          },
        ],
      }
    },
  }
  &lt;/script&gt;
  
  </code></pre>
  <p>In my method which sends the form to the API, I could check the value of each combobox and convert to an object if needed, but I am wondering if it's possible to handle it in the combobox component.</p>