icingaweb2/modules/monitoring/application/views/scripts/show/components/customvars.phtml

<?php

foreach ($object->customvars as $name => $value) {

    printf(
        '<tr><th>%s</th><td class="customvar">%s</td></tr>' . "\n",
        $this->escape($name),
        $this->customvar($value)
    );
}