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class NestableDelegate {
    /**
     * Trims the stack frames. The first set is left untouched. The rest
     * of the frames are truncated from the bottom by comparing with
     * one just on top.
     *
     * @param stacks The list containing String[] elements
     * @since 2.0
     */
    protected void trimStackFrames(List stacks) {
         for (int size=stacks.size(), i=size-1; i > 0; i--) {
             String[] curr = (String[]) stacks.get(i);
             String[] next = (String[]) stacks.get(i-1); 
             
             List currList = new ArrayList(Arrays.asList(curr));
             List nextList = new ArrayList(Arrays.asList(next));
             ExceptionUtils.removeCommonFrames(currList, nextList);

             int trimmed = curr.length - currList.size();
             if (trimmed > 0) {
                 currList.add("\t... "+trimmed+" more");
                 stacks.set(
                     i, 
                     currList.toArray(new String[currList.size()])
                 );
             }
         }
     }

}