docs: public void set(double x, double y) {
  		assert Vector2D.isUnitVector(x, y) : AssertMessages.normalizedParameters(0, 1);
  		if ((x != getX() || y != getY()) && !isBound()) {
  			final Vector2dfx v = super.get();
  			v.set(x, y);
  			fireValueChangedEvent();
  		}
  	}