@Override
    public KeyValueWriter getWriter() throws IOException {
        return new KeyValueWriter() {
            @SuppressWarnings("unchecked")
            @Override
            public void write(Object key, Object value) throws IOException {
                throw new IOException("NullMROutput is not configured for actual rows");
            }
        };
    }
Get a key value write to write Map Reduce compatible output
ql/src/java/org/apache/hadoop/hive/ql/exec/tez/NullMROutput.java