PageBuilderService dependency?

[Metricus]

What dependency do I need in POM.xml in order to use 

import com.atlassian.webresource.api.assembler.PageBuilderService ?

I have:

        <dependency>

            <groupId>com.atlassian.plugins</groupId>

            <artifactId>atlassian-plugins-webresource</artifactId>

            <version>6.0.5</version>

        </dependency>  

but the plugin fails to load