code: public static Map<String, IAminoAcid> getHashMapByThreeLetterCode() {
          AminoAcid[] monomers = createAAs();
          Map<String, IAminoAcid> map = new HashMap<String, IAminoAcid>();
          for (int i = 0; i < monomers.length; i++) {
              map.put((String) monomers[i].getProperty(RESIDUE_NAME), monomers[i]);
          }
          return map;
      }
docs: Returns a HashMap where the key is one of GLY, ALA, VAL, LEU, ILE, SER,
  THR, CYS, MET, ASP, ASN, GLU, GLN, ARG, LYS, HIS, PHE, TYR, TRP AND PRO.