LineBuffer lb = new LineBuffer();
OverLayOp op = new OverLayOp();
// Polygon pg2 = lb.lineStringBuffer((LineString) g2, 0.1);
Polygon pg3 = lb.lineStringBuffer((LineString) g3, 0.1);
Polygon pg4 = lb.lineStringBuffer((LineString) g4, 0.1);
// PointBuffer pb = new PointBuffer();
// Polygon pg3 = pb.createBuffer(l2.firstPoint(), 0.1);
// Polygon pgr = op.computeUnion(pg3, pg4).getGeometry(0);