fromJSON method
Restores this instance from the given JSON object.
Implementation
@override
Vehicle fromJSON(Map<String,dynamic> json ) {
super.fromJSON( json );
mass = json['mass'];
maxForce = json['maxForce'];
steering = SteeringManager( this ).fromJSON( json['steering'] );
smoother = json['smoother'] != null? Smoother().fromJSON( json['smoother'] ) : null;
return this;
}