How to take distance transfrom to meters?UTM'unit is meters?



    private static CRSFactory crsFactory = new CRSFactory();
    private static CoordinateReferenceSystem WGS84 = crsFactory.createFromName("epsg:4326");
    private static CoordinateReferenceSystem UTM = crsFactory.createFromName("epsg:25833");
    private static CoordinateTransformFactory ctFactory = new CoordinateTransformFactory();
    private static CoordinateTransform wgsToUtm = ctFactory.createTransform(WGS84, UTM);

    public static Boolean pointInsidePolygonWithMargin(double lon, double lat,double margin, double[][] polygonPoints){

        Coordinate[] polygonCoordinates = new Coordinate[polygonPoints.length+1];
        for ( int i = 0 ; i < polygonPoints.length ; i++ ){
            ProjCoordinate wtu = new ProjCoordinate();
            wgsToUtm.transform(new ProjCoordinate(polygonPoints[i][0], polygonPoints[i][1]), wtu);
            polygonCoordinates[i] = new Coordinate(wtu.x,wtu.y);
        }
        //闭合
        polygonCoordinates[polygonPoints.length] = polygonCoordinates[0];
        ProjCoordinate current = new ProjCoordinate();
        wgsToUtm.transform(new ProjCoordinate(lon, lat), current);

        // 创建多边形对象和当前位置对象
        GeometryFactory geometryFactory = new GeometryFactory();
        Polygon polygon = geometryFactory.createPolygon(polygonCoordinates);
        Point currentLocation = geometryFactory.createPoint(new Coordinate(current.x, current.y));

        // 使用PreparedGeometryFactory提高计算性能
        PreparedGeometryFactory preparedGeometryFactory = new PreparedGeometryFactory();
        PreparedGeometry preparedPolygon = preparedGeometryFactory.create(polygon);
        boolean pointInsidePolygon = currentLocation.within(preparedPolygon.getGeometry());
        if( pointInsidePolygon ){
            // 创建STRtree空间索引
            STRtree index = new STRtree();
            for (int i = 0; i < polygonCoordinates.length - 1; i++) {
                Coordinate edgeStart = polygonCoordinates[i];
                Coordinate edgeEnd = polygonCoordinates[i + 1];
                LineString edge = geometryFactory.createLineString(new Coordinate[]{edgeStart, edgeEnd});
                index.insert(edge.getEnvelopeInternal(), edge);
            }
            index.build();
            // 计算点到多边形边界的最短距离
            double shortestDistance = Double.POSITIVE_INFINITY;
            for (Object edgeObj : index.query(currentLocation.getEnvelopeInternal())) {
                LineString edge = (LineString) edgeObj;
                double distance = edge.distance(currentLocation);
                if (distance < shortestDistance) {
                    shortestDistance = distance;
                }
            }
            System.out.println("当前位置到多边形边界的最短距离：" + shortestDistance + " meters ???");
            return shortestDistance <= margin;
        }else{
            return false;
        }
    }

`

How to take distance transfrom to meters?
UTM'unit  is meters? 
Why is there a 4-meter discrepancy between my calculated result and the correct one?
locationtech / jts

How to take distance transfrom to meters?UTM'unit is meters? #1017
