code: public static Normalizer2WithImpl getN2WithImpl(int index) {
          switch(index) {
          case 0: return getNFCInstance().decomp;  // NFD
          case 1: return getNFKCInstance().decomp; // NFKD
          case 2: return getNFCInstance().comp;    // NFC
          case 3: return getNFKCInstance().comp;   // NFKC
          default: return null;
          }
      }
docs: For use in properties APIs.