A whiteSpace facet that relaxed its base type's effective whiteSpace was
accepted; XSD Part 2 4.3.6 permits only strengthening, ordered
preserve < replace < collapse. A base fixed to collapse admits only collapse,
and a replace base admits replace or collapse; relaxing it (e.g. replace over a
collapse base, or restricting xs:token to replace) is now rejected. The base's
effective whiteSpace is its own facet falling back to its built-in intrinsic;
the check is atomic-only and, when a base's own whiteSpace has not yet resolved,
can only under-detect (an unresolved base defaults to preserve, the weakest), so
it never rejects a valid restriction.
XSTS: invalid schemas accepted 422 to 413, no other bucket raised.