/**
* A physical person, aggregated from the various {@link Persona}s the person
- * might have, such as their different IM addresses or vCard entries.
+ * might have, such as their different IM addresses or vCard entries. An
+ * individual must always contain at least one {@link Persona}.
*
* When choosing the values of single-valued properties (such as
* {@link Individual.alias} and {@link Individual.avatar}; but not multi-valued
/**
* The set of {@link Persona}s encapsulated by this Individual.
*
+ * There must always be at least one Persona in this set.
+ *
* No order is specified over the set of personas, as such an order may be
* different across each of the properties implemented by the personas (e.g.
* should they be ordered by presence, name, star sign, etc.?).