docs: public static String TileXYToQuadKey(final int tileX, final int tileY, final int levelOfDetail) {
  		final char[] quadKey = new char[levelOfDetail];
  		for (int i = 0 ; i < levelOfDetail;  i++) {
  			char digit = '0';
  			final int mask = 1 << i;
  			if ((tileX & mask) != 0) {
  				digit++;
  			}
  			if ((tileY & mask) != 0) {
  				digit++;
  				digit++;
  			}
  			quadKey[levelOfDetail - i - 1] = digit;
  		}
  		return new String(quadKey);
  	}