delete method
Delete a property. Returns true if the property was deleted, false if the property didn't already exist
Implementation
bool delete(MqttIProperty property) {
var ok = false;
if (property.identifier != MqttPropertyIdentifier.userProperty) {
ok = _container.remove(property.identifier) != null;
} else {
ok = _userProperties.remove(property);
}
return ok;
}