private static Set<String> retrieveValues(final String key,final Map<String,Set<String>> keyValueMap){
  return keyValueMap.containsKey(key) ? keyValueMap.get(key) : Collections.<String>emptySet();
}

private static Set < String > retrieveValues ( final String key , final Map < String , Set < String > > keyValueMap ) { return keyValueMap . containsKey ( key ) ? keyValueMap . get ( key ) : Collections . < String > emptySet ( ) ; }
helper method to retrieve the set of strings from the passed key / value map .
