Group @testable imports at the bottom, per public/rules-swift's swiftformat. A
behavior-preserving import-ordering reformat across 252 files (mostly tests).
--trailingclosures was deliberately not adopted (cosmetic, and swiftformat flags
it as caution-worthy).
A complex type's effective {attribute wildcard} is the intersection of the
anyAttribute wildcards it draws from its own declaration and each referenced
attribute group (XSD 1.0 cos-aw-intersect), not their union. An attribute is
admitted only if every source admits it, so two attribute groups constraining
disjoint namespaces admit nothing and an attribute in either is rejected.
attributeWildcard(under:_:visited:) combined the sources with Wildcard.union,
which let through an attribute that only one source allowed. It now uses a new
Wildcard.intersection covering the namespace cases (##any identity, enumerated
set intersection, enumerated-with-##other exclusion via exclude(_:otherThan:)).
A type with a single anyAttribute source is unchanged (intersection with the
nil identity is the lone wildcard), and a complexContent extension's union with
its base wildcard (XSDComplexContent) is untouched. The inexpressible
##other/##other-different-target and mismatched processContents cases resolve to
the less restrictive result, so the change never over-rejects.
XSTS invalid-instances-accepted 94 to 89, no false positive (valid-instances-
rejected and valid-schemas-rejected held at 0 across the whole corpus), no other
bucket moved. An adversarial review exercised nested groups, ##other/##local and
cross-import namespace cases, processContents, extension-vs-restriction, and
single-source invariance, and found no new over-rejection.
