code: private List<IBond> findUnspecifiedDoubleBonds(int[][] adjList) {
          List<IBond> unspecifiedDoubleBonds = new ArrayList<>();
          for (IBond bond : container.bonds()) {
              // non-double bond, ignore it
              if (bond.getOrder() != DOUBLE)
                  continue;
  
              final IAtom aBeg = bond.getBegin();
              final IAtom aEnd = bond.getEnd();
  
              final int beg = atomToIndex.get(aBeg);
              final int end = atomToIndex.get(aEnd);
  
              // cyclic bond, ignore it (FIXME may be a cis/trans bond in macro cycle |V| > 7)
              if (ringSearch.cyclic(beg, end))
                  continue;
  
              // stereo bond, ignore it depiction is correct
              if ((doubleBondElements[beg] != null && doubleBondElements[beg].getStereoBond().equals(bond)) ||
                      (doubleBondElements[end] != null && doubleBondElements[end].getStereoBond().equals(bond)))
                  continue;
  
              // is actually a tetrahedral centre
              if (tetrahedralElements[beg] != null || tetrahedralElements[end] != null)
                  continue;
  
              if (!isCisTransEndPoint(beg) || !isCisTransEndPoint(end))
                  continue;
  
              if (!hasOnlyPlainBonds(beg, bond) || !hasOnlyPlainBonds(end, bond))
                  continue;
  
              if (hasLinearEqualPaths(adjList, beg, end) || hasLinearEqualPaths(adjList, end, beg))
                  continue;
  
              unspecifiedDoubleBonds.add(bond);
          }
          return unspecifiedDoubleBonds;
      }
docs: Locates double bonds to mark as unspecified stereochemistry.
  
  @return set of double bonds