@Override
      public void write(char[] cbuf, int off, int len) throws IOException {
        writer.write(cbuf, off, len);
      }
Notice that, closing the return {@link Writer} will not close the {@code writer} passed in, you
still need to close the {@code writer} by yourself.
<p/>
This is because that, we can only finish the json after you call {@link Writer#close()}. So if
we just close the {@code writer}, you can write nothing after finished the json.
hbase-http/src/main/java/org/apache/hadoop/hbase/util/JSONBean.java