code: private String getSha1(String name, String version) {
          if (dotHexCachePath == null || name == null || version == null){
              logger.warn("Can't calculate SHA1, missing information: .hex-cache = {}, name = {}, version = {}", dotHexCachePath, name, version);
              return null;
          }
          File tarFile = new File(dotHexCachePath + fileSeparator + name + Constants.DASH + version + TAR_EXTENSION);
          try {
              return ChecksumUtils.calculateSHA1(tarFile);
          } catch (IOException e) {
              logger.warn("Failed calculating SHA1 of {}.  Make sure HEX is installed", tarFile.getPath());
              logger.debug("Error: {}", e.getStackTrace());
              return null;
          }
      }
docs: this method is used when there's a known version