Distinct system names, sorted. Empty when the model genuinely has no
IfcClassification entities — check unresolved before reading an
empty array as "no systems".
True when the model DOES have IfcClassification entities (per the
byType index) but their Name could not be read because this store
has no source bytes — a server-parsed store (issue #3948), the same
condition extractClassificationsOnDemand signals per-entity via
ClassificationInfo.unresolved. An effective view may still supply
complete authored names alongside unreadable source systems. When
true, names is incomplete and cannot establish a system's absence.
Result of extractClassificationSystemsOnDemand.