Magento 2 - Plugins on some classes don't work in etc/frontend/di.xml

Question

I'm trying to do this:

<type name="Magento\Payment\Model\MethodList">
    <plugin name="a_name_plugin" type="Mynamespace\Mymodule\Plugin\Model\Payment\MethodList\Plugin" sortOrder="10"/>
</type>

It isn't activated if I place this declaration in etc/frontend/di.xml. But it works in etc/di.xml. I want it to be active only on frontend.

Why it would not work from etc/frontend/di.xml or how to make it work ?

Using Magento 2.0.7 Magento mode is developer. Cache should not be a problem. var/generation/* was cleaned a few times.

Thank you

Answer 1

most probably you are not actually in the frontend area: try putting it into etc/webapi_rest/di.xml