build method
Implementation
Event build() {
if (_customerId == null || _customerId!.isEmpty) {
throw ArgumentError('Customer ID cannot be empty');
}
if (_events.isEmpty) {
throw ArgumentError('At least one event must be specified');
}
return Event._(
events: Map<String, Map<String, Object>>.from(_events),
customerId: _customerId!,
mobile: _mobile,
email: _email,
);
}