vector3.java

public final class Vector3 {
 
  public final float x;
  public final float y;
  public final float z;
 
  public Vector3(float x, float y, float z) {
    this.x = x;
    this.y = y;
    this.z = z;
  }
 
  public Vector3 add(final Vector3 v) {
    return new Vector2(x + v.x, y + v.y, z + v.z);
  }
 
  // toString, hashCode, equals...
}

Looks like there is a typo, at L14. Vector2 -> Vector3