Before this change MvcUriComponentsBuilder could not create a
UriComponentsBuilder for methods where the mapping has a URI variable
and no matching method argument for it.
For example a URI variable may be in the type-level mapping but not
all methods may have an @PathVariable argument for it.
This fix addresses the shortcoming such that MvcUriComponentsBuilder
expands the method argument values available to it and leaves remaining
URI variables to be further expanded via UriComponents.expand().
Issue: SPR-11391
42d0470d94