resultSet = vars.getObject("resultSet")
result = new StringBuilder()

for (Object row : resultSet ) {
    iter = row.entrySet().iterator()
    while (iter.hasNext()) {
        pair = iter.next()
        result.append(pair.getValue())
        result.append(",")
    }
    result.append(System.getProperty("line.separator"))
}

org.apache.commons.io.FileUtils.writeStringToFile(new File("foo.csv"), result.toString(), "UTF-8")