code: public static BoundingBox getWebMercatorBoundingBox(long x, long y, int zoom) {
  
  		double tileSize = tileSizeWithZoom(zoom);
  
  		double minLon = (-1 * ProjectionConstants.WEB_MERCATOR_HALF_WORLD_WIDTH)
  				+ (x * tileSize);
  		double maxLon = (-1 * ProjectionConstants.WEB_MERCATOR_HALF_WORLD_WIDTH)
  				+ ((x + 1) * tileSize);
  		double minLat = ProjectionConstants.WEB_MERCATOR_HALF_WORLD_WIDTH
  				- ((y + 1) * tileSize);
  		double maxLat = ProjectionConstants.WEB_MERCATOR_HALF_WORLD_WIDTH
  				- (y * tileSize);
  
  		BoundingBox box = new BoundingBox(minLon, minLat, maxLon, maxLat);
  
  		return box;
  	}
docs: Get the Web Mercator tile bounding box from the Google Maps API tile
  coordinates and zoom level
  
  @param x
  x coordinate
  @param y
  y coordinate
  @param zoom
  zoom level
  @return bounding box