code: private boolean matchPostagRegexp(AnalyzedTokenReadings aToken, Pattern pattern) {
      for (AnalyzedToken analyzedToken : aToken) {
        String posTag = analyzedToken.getPOSTag();
        if (posTag == null) {
          posTag = "UNKNOWN";
        }
        final Matcher m = pattern.matcher(posTag);
        if (m.matches()) {
          return true;
        }
      }
      return false;
    }
docs: Match POS tag with regular expression