code: private String getChunkChecksum(File chunkFile) {
          try {
              return checksumUtil.generateChecksum(chunkFile);
          } catch (IOException e) {
              throw new DuraCloudRuntimeException("Unable to generate checksum for file " +
                                                  chunkFile + " due to: " + e.getMessage());
          }
      }
docs: /*
  Determine the checksum of the chunk file