public static Hashtable<String,CharSet> releaseExpressionCache(){
  Hashtable<String,CharSet> result=expressionCache;
  expressionCache=null;
  return result;
}

public static Hashtable < String , CharSet > releaseExpressionCache ( ) { Hashtable < String , CharSet > result = expressionCache ; expressionCache = null ; return result ; }
returns a copy of charset ' s expression cache and sets charset ' s expression cache to empty .
