code: public String getInchiKey() throws CDKException {
          JniInchiOutputKey key;
          try {
              key = JniInchiWrapper.getInchiKey(output.getInchi());
              if (key.getReturnStatus() == INCHI_KEY.OK) {
                  return key.getKey();
              } else {
                  throw new CDKException("Error while creating InChIKey: " + key.getReturnStatus());
              }
          } catch (JniInchiException exception) {
              throw new CDKException("Error while creating InChIKey: " + exception.getMessage(), exception);
          }
      }
docs: Gets generated InChIKey string.