presto-geospatial/src/main/java/io/prestosql/plugin/geospatial/GeoFunctions.java/GeoFunctions/stXMax
class GeoFunctions:    @SqlNullable
    @Description("Returns X maxima of a bounding box of a Geometry")
    @ScalarFunction("ST_XMax")
    @SqlType(DOUBLE)
    public static Double stXMax(@SqlType(GEOMETRY_TYPE_NAME) Slice input)
    {
        Envelope envelope = deserializeEnvelope(input);
        if (envelope == null) {
            return null;
        }
        return envelope.getXMax();
    }