StubEnumCaseReference

Placeholder for an enum-case value that the host runtime cannot materialize because the declaring extension is not loaded in the cache-generating process (e.g. ext-uri is absent on the Windows host that regenerates the cache).

An enum-case default such as \Uri\UriComparisonMode::ExcludeFragment is normally resolved at runtime via constant() to the enum instance, which the serializer renders as "[object:Uri\UriComparisonMode]". When the extension is missing, constant() fails and the case cannot be reconstructed (a pure enum case has no scalar value). This reference carries the declaring enum's FQN so the serializer can emit the identical, environment-independent string instead of letting the default silently degrade to null.