NelmioApiDocBundle/Resources/config/swagger_php.xml

<?xml version="1.0" ?>
<container xmlns="http://symfony.com/schema/dic/services"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">

    <services>
        <service id="nelmio_api_doc.describers.swagger_php" class="Nelmio\ApiDocBundle\Describer\SwaggerPhpDescriber" public="false">
            <argument>%kernel.root_dir%</argument>
            <call method="setOperationResolver">
              <argument type="service" id="nelmio_api_doc.describers.swagger_php.operation_resolver" />
            </call>

            <tag name="nelmio_api_doc.describer" priority="-300" />
        </service>

        <service id="nelmio_api_doc.describers.swagger_php.operation_resolver" class="Nelmio\ApiDocBundle\SwaggerPhp\OperationResolver" public="false">
            <argument type="service">
                <service class="Symfony\Component\Routing\RouteCollection">
                    <factory service="router" method="getRouteCollection" />
                </service>
            </argument>
            <argument type="service" id="nelmio_api_doc.controller_reflector" />
        </service>
    </services>

</container>