code: public URI getInputFile() {
  //        if (prop.containsKey(PROPERTY_INPUT_MAP_URI)) {
  //            return toURI(prop.get(PROPERTY_INPUT_MAP_URI).toString());
  //        }
  //        return null;
          return files.values().stream()
                  .filter(fi -> fi.isInput)
                  .map(fi -> fi.src)
                  .findAny()
                  .orElse(null);
  
      }
docs: Get input file path.
  @return absolute input file path, {@code null} if not set