isSecondary property

Whether this is a domain for a secondary app, meaning that any subdomain provided is significant and will be stored as part of the domain. This is useful for supporting multiple apps (one primary and multiple secondaries) on the same root domain (eTLD+1).

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.