core/templates/_partials/fields/data.html.twig

{% extends '@bolt/_partials/fields/_base.html.twig' %}

{% set postfix = "<strong>Note:</strong> This Field contains internal data, likely added / maintained programmatically. You cannot edit this data." %}
{% set value = field.value|json_encode %}

{% block field %}
<div class="editor--data">
<input type="hidden" id="{{ id }}" name="{{ name }}" value="{{ value }}" />
<pre>
{{ field.value|json_encode(constant('JSON_PRETTY_PRINT')) }}
</pre>
</div>
{% endblock %}