proj4.defs("EPSG:32633", "+proj=utm +zone=33 +datum=WGS84 +units=m +no_defs");
proj4.defs('WGS84', "+title=WGS 84 (long/lat) +proj=longlat +ellps=WGS84 +datum=WGS84 +units=degrees");
...
nodes.forEach(n => {
    var position = n.position;
    n.position = proj4('EPSG:32633', 'WGS84', position);
});

private static final CoordinateTransform transfGPS;

static {
    final CoordinateTransformFactory ctFactory = new CoordinateTransformFactory();
    final CRSFactory crsFactory = new CRSFactory();
    final CoordinateReferenceSystem projWGS84 =
                                              crsFactory.createFromParameters("WGS84",
                                                                              "+title=long/lat:WGS84 +proj=longlat +ellps=WGS84 +datum=WGS84 +units=degrees");
    final CoordinateReferenceSystem projEPSG32633 =
                                                  crsFactory.createFromParameters("EPSG:32633",
                                                                                  "+proj=utm +zone=33 +datum=WGS84 +units=m +no_defs");

    transfGPS = ctFactory.createTransform(projWGS84, projEPSG32633);
}

public static Point epanetToGps(Point position) {
    ProjCoordinate p1 = new ProjCoordinate();
    ProjCoordinate p2 = new ProjCoordinate();
    p1.x = position.getX();
    p1.y = position.getY();

    transfGPS.transform(p1, p2);
    return new Point(p2.x, p2.y);
}