private static String getRow(StringBuilder sb, TokenDFTF tp) {
        sb.setLength(0);
        sb.append(clean(tp.token));
        sb
                .append("\t")
                .append(tp.df);
        sb
                .append("\t")
                .append(tp.tf);
        return sb.toString();
    }
Utility class that reads in a UTF-8 input file with one document per row
and outputs the 20000 tokens with the highest document frequencies.
<p>
The CommmonTokensAnalyzer intentionally drops tokens shorter than 4 characters,
but includes bigrams for cjk.
<p>
It also has a include list for __email__ and __url__ and a skip list
for common html markup terms.
tika-eval/tika-eval-app/src/main/java/org/apache/tika/eval/app/tools/TopCommonTokenCounter.java