code: public IAtomContainer getUnsetAtomsInAtomContainer(IAtom atom, IAtomContainer ac) {
          List atoms = ac.getConnectedAtomsList(atom);
          IAtomContainer connectedAtoms = atom.getBuilder().newInstance(IAtomContainer.class);
          for (int i = 0; i < atoms.size(); i++) {
              IAtom curAtom = (IAtom) atoms.get(i);
              if (!curAtom.getFlag(CDKConstants.ISPLACED)) {//&& atoms[i].getPoint3d() == null) {
                  connectedAtoms.addAtom(curAtom);
              }
          }
          return connectedAtoms;
      }
docs: Gets the unsetAtomsInAtomContainer attribute of the
  AtomTetrahedralLigandPlacer3D object.
  
  @param  atom  Description of the Parameter
  @param  ac    Description of the Parameter
  @return       The unsetAtomsInAtomContainer value