runtime property
Runtime asks for an isolation: runc, gvisor, kata-clh or kata-fc. It is a REQUEST, not a guarantee — the sandbox that comes back carries the runtime it was actually given, which is the field to read.
Please note: This property should have been non-nullable! Since the specification file does not include a default value (using the "default:" property), however, the generated source code must fall back to having a nullable type. Consider adding a "default:" property in the specification file to hide this note.
Implementation
String? runtime;