code: public static int getImplicitHydrogenCount(IAtomContainer atomContainer, IAtom atom) {
          return atom.getImplicitHydrogenCount() == CDKConstants.UNSET ? 0 : atom.getImplicitHydrogenCount();
      }
docs: Returns The number of Implicit Hydrogen Count for a given IAtom.
  @param atomContainer
  @param atom
  @return Implicit Hydrogen Count