Marker for AOP proxy interfaces (in particular: introduction interfaces)
that explicitly intend to return the raw target object (which would normally
get replaced with the proxy object when returned from a method invocation).
Note that this is a marker interface in the style of
semantically applying to a declared interface rather than to the full class
of a concrete object. In other words, this marker applies to a particular
interface only (typically an introduction interface that does not serve
as the primary interface of an AOP proxy), and hence does not affect
other interfaces that a concrete AOP proxy may implement.