code: private void decideBondOrder(IAtomContainer atomContainer, int start) throws CDKException {
          for (int i = 0; i < atomContainer.getBondCount(); i++)
              if (atomContainer.getBond(i).getFlag(CDKConstants.SINGLE_OR_DOUBLE))
                  atomContainer.getBond(i).setOrder(IBond.Order.SINGLE);
  
          for (int i = start; i < atomContainer.getBondCount(); i++) {
              checkBond(atomContainer, i);
          }
          /*
           * If we don't start with first bond, then we have to check the bonds
           * before the bond we started with.
           */
          if (start > 0) {
              for (int i = start - 1; i >= 0; i--) {
                  checkBond(atomContainer, i);
              }
          }
      }
docs: This method decides the bond order on bonds that has the
  <code>SINGLE_OR_DOUBLE</code>-flag raised.
  
  @param atomContainer The molecule to investigate
  @param start The bond to start with
  @throws CDKException