如何制作lucene TokenStream对象的深层副本

Question

我正在尝试创建一个自定义solr过滤器，它只保留具有最大整数值的标记。在这样做的时候，到目前为止我编写了以下代码：

public final class MaxValueTokenFilter extends TokenFilter {

    private final CharTermAttribute termAttribute = addAttribute(CharTermAttribute.class);  

    public MaxValueTokenFilter(TokenStream in) {
        super(in);
    }

    @Override
    public boolean incrementToken() throws IOException {

        TokenStream clonedTokenStream = DeepCopy???(input);

        int maxVal = 0;

        //increamenting the clonedTokenStream should not increment the actual tokenStream
        while (clonedToken.incrementToken()) {      
            final String term = termAttribute.toString();      
            int currentNumber = Integer.parseInt(term);
            if(currentNumber > maxVal)
            {       
                maxVal = currentNumber;  
            }
        }

        //increment the actual token to match the maximum value
        while (input.incrementToken()) {        
            final String term = termAttribute.toString();      
            int currentNumber = Integer.parseInt(term);
            if(currentNumber == maxVal)
            {       
                return true;    
            }
        }

        return false;
    }

    @Override
    public void reset() throws IOException {
        super.reset();
    }
}

有人可以帮我制作TokenStream对象的DeepCopy，这样增加复制的TokenStream就不会增加实际的TokenStream。