code: public void registerExistingChecksums(File featureDir, String symbolicName, String fileName) {
          ChecksumData checksums = checksumsMap.get(featureDir);
          if (checksums == null) {
              checksums = new ChecksumData();
              checksumsMap.put(featureDir, checksums);
          }
          checksums.registerExistingChecksums(symbolicName, fileName);
      }
docs: Registers an existing feature directory's checksum
  
  @param featureDir the feature directory
  @param symbolicName the symbolic name for the file
  @param fileName the actual file name