code: public synchronized void addTile( int x, int y, int z, byte[] imageBytes ) throws Exception {
          database.execOnConnection(connection -> {
              try (IHMPreparedStatement pstmt = connection.prepareStatement(insertTileSql);) {
                  pstmt.setInt(1, z);
                  pstmt.setInt(2, x);
                  pstmt.setInt(3, y);
                  pstmt.setBytes(4, imageBytes);
                  pstmt.executeUpdate();
                  return "";
              }
          });
      }
docs: Add a single tile.
  
  @param x the x tile index.
  @param y the y tile index.
  @param z the zoom level.
  @return the tile image bytes.
  @throws Exception