The constructor of the polygon class uses a traditional pre Java 5 array parameter which requires you to declare double arrays to set the coordinates as follows:

Polygon polygon = new Polygon(
new double[] {
1.0, 2.0, 3.0
}
);

I request that the signature of the Polygon constructor is changed to support var args, thereby allowing me to write

Polygon polygon = new Polygon(1.0, 2.0, 3.0);

If you think about it, this is a low cost / high benefit issue - it is a very small code change which will save all Java FX developers some typing.