Hi, I hope you are all fine! 
I wass reading the Builder content. The getResult() method of the code below returns a IAircraft. Where is the code of this class?
public abstract class AircraftBuilder {
public void buildEngine() {
}
public void buildWings() {
}
public void buildCockpit() {
}
public void buildBathrooms() {
}
abstract public **IAircraft** getResult();
}