code: public static int[] getBondCoordinates(IBond bond) {
          if (bond.getBegin().getPoint2d() == null || bond.getEnd().getPoint2d() == null) {
              logger.error("getBondCoordinates() called on Bond without 2D coordinates!");
              return new int[0];
          }
          int beginX = (int) bond.getBegin().getPoint2d().x;
          int endX = (int) bond.getEnd().getPoint2d().x;
          int beginY = (int) bond.getBegin().getPoint2d().y;
          int endY = (int) bond.getEnd().getPoint2d().y;
          return new int[]{beginX, beginY, endX, endY};
      }
docs: Writes the coordinates of the atoms participating the given bond into an
  array.
  See comment for center(IAtomContainer atomCon, Dimension areaDim, HashMap renderingCoordinates) for details on coordinate sets
  
  @param  bond  The given bond
  @return       The array with the coordinates