ResourceEnricherInvokingHandlerAdapter now has a copy constructor to
allow setting it up from a default RequestMappingHandlerAdapter. The
reason we introduce this is that WebMvcConfigurationSupport unfortunately
does not allow customizing the handler adapter class to be used as its
instantiations is buried in a method with more setup code. With the copy
constructor introduced one can simply take the configured instance
WebMvcConfigurationSupport provides and pipe it into the custom
ResourceEnricherInvokingHandlerAdapter.