You are using IntelliJ IDEA and have performed a refactor operation. Which functionality may have been used to convert the code from before state to after state?

Before:

public class Rectangle { private int length, width; public Rectangle(int length, int width) { this.length = length; this.width = width; } }

After: 

public class Rectangle { private int length, width; private Rectangle(int length, int width) { this.length = length; this.width = width; } public static Rectangle createRectangle(int length, int width) { return new Rectangle(length, width); } }