xmpp.chapril.org-conversejs/src/templates/form_checkbox.html

<div class="form-group">
    <input id="{{{o.id}}}" name="{{{o.name}}}" type="checkbox" {{{o.checked}}} {[ if (o.required) { ]} required {[ } ]} >
    <label class="form-check-label" for="{{{o.id}}}">{{{o.label}}}</label>
</div>