code: @Override
      public boolean contains(IAtom atom) {
          if (atoms == null) return false;
          for (IAtom localAtom : atoms) {
              if (localAtom.equals(atom)) return true;
          }
          return false;
      }
docs: Returns true if the given atom participates in this bond.
  
  @param atom The atom to be tested if it participates in this bond
  @return true if the atom participates in this bond