{
    "batchcomplete": "",
    "query": {
        "slotroles": {
            "main": {
                "defined": "",
                "slot_role_layout": {
                    "display": "section",
                    "region": "center",
                    "placement": "append"
                },
                "content_model": "wikitext"
            },
            "jsondata": {
                "defined": "",
                "slot_role_layout": {
                    "display": "details",
                    "region": "footer",
                    "placement": "append"
                },
                "content_model": "json"
            },
            "deprecated": {
                "slot_role_layout": {
                    "display": "section",
                    "region": "center",
                    "placement": "append"
                },
                "content_model": "unknown"
            }
        }
    }
}

$result = $module->getResult();
$data = [];

$slotRoleRegistry = MediaWikiServices::getInstance()->getSlotRoleRegistry();
$definedRoles = $slotRoleRegistry->getDefinedRoles();
$knownRoles = $slotRoleRegistry->getKnownRoles();

foreach ( $knownRoles as $slotName ) {
	$defined = in_array( $slotName, $definedRoles );
	$slotRoleHandler = $slotRoleRegistry->getRoleHandler( $slotName );
	$data[$slotName]['defined'] = $defined;
	$data[$slotName]['slot_role_layout'] = $slotRoleHandler->getOutputLayoutHints();
	$data[$slotName]['content_model'] = $slotRoleHandler->getDefaultModel(Title::newFromDBkey(  "Main_Page" ));
}

$result->addValue(['query'], 'slots', $data);