How to make Yii2 rest api use json output by default? -

i've configured rest api this: http://www.yiiframework.com/doc-2.0/guide-rest-quick-start.html

how make yii2 rest api output json default instead of xml?

from client use:

curl -i -h "accept:application/json" "http://localhost/myendpoint" 

it seem json should default, yii2 it's xml. see:

restful response how return json instead of xml in yii2?

and/or dig deeper docs: http://yiiframework.com/doc-2.0/yii-filters-contentnegotiator.html