code: public IAtom getUnplacedRingHeavyAtom(IAtomContainer molecule, IAtom atom) {
          List<IBond> bonds = molecule.getConnectedBondsList(atom);
          IAtom connectedAtom = null;
          for (IBond bond : bonds) {
              connectedAtom = bond.getOther(atom);
              if (isUnplacedHeavyAtom(connectedAtom) && connectedAtom.getFlag(CDKConstants.ISINRING)) {
                  return connectedAtom;
              }
          }
          return connectedAtom;
      }
docs: Gets the unplacedRingHeavyAtom attribute of the AtomPlacer3D object.
  
  @param molecule
  @param  atom  Description of the Parameter
  @return       The unplacedRingHeavyAtom value