code: public static double[] metersToLatLon( double mx, double my ) {
  
          double lon = (mx / originShift) * 180.0;
          double lat = (my / originShift) * 180.0;
  
          lat = 180 / Math.PI * (2 * Math.atan(Math.exp(lat * Math.PI / 180.0)) - Math.PI / 2.0);
          return new double[]{-lat, lon};
      }
docs: Converts XY point from Spherical Mercator EPSG:900913 to lat/lon in WGS84
  Datum
  
  @param mx x
  @param my y
  @return lat long