public static synchronized void registerAdditionalHyphenationFileDirectory(String directory){
  if (additionalHyphenationFileDirectories == null) {
    additionalHyphenationFileDirectories=new ArrayList<>();
  }
  additionalHyphenationFileDirectories.add(directory);
}

public static synchronized void registerAdditionalHyphenationFileDirectory ( String directory ) { if ( additionalHyphenationFileDirectories == null ) { additionalHyphenationFileDirectories = new ArrayList < > ( ) ; } additionalHyphenationFileDirectories . add ( directory ) ; }
registers additional file directories .
