How to open a v-list-group by default?

How to open a v-list-group by default?

I tried value as it says in the documentation:

So this is my simplified Vuetify 3 (3.3.14) code using value trying to expand the v-list-group by default:

<v-list>
  <v-list-group :value="isOpen1">
    <template v-slot:activator="{ props }">
      <v-list-item/>
    </template>
    <v-list-item/>
  </v-list-group>
  <v-list-group :value="isOpen2">
    <template v-slot:activator="{ props }">
      <v-list-item/>
    </template>
    <v-list-item/>
  </v-list-group>
</v-list>

...

export default {
  data() {
    return {
      isOpen1: true,
      isOpen2: true
    }
  }
}

But now it is closed by default and when I open (expand) either of the two v-list-group items, both are opened.

The value prop on the v-list-group sets an identifier for the group. Using the opened prop on the surrounding list, you can pass in an array with group identifiers to indicate which groups are opened:

<v-list v-model:opened="openedGroups">
  <v-list-group value="group1">
    ...
  </v-list-group>
  <v-list-group value="group2">
    ...
  </v-list-group>
</v-list>

and

export default {
  data() {
    return {
      openedGroups: ['group1']
    }
  }
}

Have a look at the example from the documentation