code: protected boolean checksumsMatch(File localFile, String remoteChecksum)
          throws IOException {
          if (remoteChecksum == null || "".equals(remoteChecksum)) {
              if (contentStream != null) {
                  remoteChecksum = contentStream.getChecksum();
              } else {
                  remoteChecksum = source.getSourceChecksum(contentItem);
              }
          }
          String localChecksum = getChecksum(localFile);
          return localChecksum.equals(remoteChecksum);
      }
docs: /*
  Checks to see if the checksums of the local file and remote file match