private static List<Vector2D> buildQuadrilateral(final Vector2D... points){
  List<Vector2D> quadrilateral=new ArrayList<Vector2D>();
  for (  Vector2D p : points) {
    if (!quadrilateral.contains(p)) {
      quadrilateral.add(p);
    }
  }
  return quadrilateral;
}

private static List < Vector2D > buildQuadrilateral ( final Vector2D ... points ) { List < Vector2D > quadrilateral = new ArrayList < Vector2D > ( ) ; for ( Vector2D p : points ) { if ( ! quadrilateral . contains ( p ) ) { quadrilateral . add ( p ) ; } } return quadrilateral ; }
build the convex quadrilateral with the found corner points ( with min / max x / y coordinates ) .
