Allows the type of the underlying object to be specified explicitly. This is used when creating scoped proxies of transactional proxies of services. The scoped proxy needs to know that type of the object before the transactional proxy factory has instantiated the underlying service and is able to determine it's class. This class allows the type to be explicitly specified. Used by org.codehaus.groovy.grails.plugins.services.ServicesGrailsPlugin.