I want to implement plugin after, before and around concept in my Magento 2 website.

**di.xml** :

    <type name="Magento\Webapi\Model\Soap\Server">
        <plugin name="soap_log" type="training\learning\Model\Webapi\Soap\Server" />
    </type>

`Magento\Webapi\Model\Soap\Server` has a method `_checkRequest` and it has a `string` type parameter.

Now i want to get that string type parameter in my `_aftercheckrRequest` in `training\learning\Model\Webapi\Soap\Server` class. How can I achieve this ?