question: public synchronized AlphabeticIndex addLabels ( Locale locale ) { addLabels ( peer , locale . toString ( ) ) ; return this ; }
target:  Adds the index characters from the given locale to the index. The labels are added to those that are already in the index; they do not replace the existing index characters. The collation order for this index is not changed; it remains that of the locale that was originally specified when creating this index.