ke_search with Mask

ext_localconf.php

<?php
// extend ke_search for mask content elements
$GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['ke_search']['modifyPageContentFields'][] = 'Vendor\\Ext\\Hooks\\SearchExtension';
$GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['ke_search']['modifyContentFromContentElement'][] = 'Vendor\\Ext\\Hooks\\SearchExtension';

SearchExtension.php

<?php
namespace Vendor/Ext/Hooks;

class SearchExtension
{
    public function modifyPageContentFields(&$fields, $pObj)
    {
        $fields .= ', subheader, tx_mask_mask_rte';
    }

    public function modifyContentFromContentElement(&$bodytext, &$ttContentRow, $pObj)
    {
        $ttContentRow['header'] .= " " . $ttContentRow['subheader'];
    }
}