peer property
Peer is the counterparty, if any. It is an aggregation axis of its own — "unfamiliar" is a fact about a relationship and not about either party.
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? peer;