How can use the /export request handler via SolrJ?

I'm using Solr 4.10.

I have enabled the /export request handler for an index by adding this to the solrconfig.xml (as mentioned here: https://cwiki.apache.org/confluence/display/solr/Exporting+Result+Sets):

<requestHandler name="/export" class="solr.SearchHandler">
  <lst name="invariants">
    <str name="rq">{!xport}</str>
    <str name="wt">xsort</str>
    <str name="distrib">false</str>
  </lst>
  <arr name="components">
    <str>query</str>
  </arr>
</requestHandler>

Now I can use: http://localhost:8983/solr/index/select?.... as well as http://localhost:8983/solr/index/export?.... from a browser or curl.

But, I cannot get it to run properly using SolrJ.

I tried (as suggested here: https://lucene.apache.org/solr/4_10_0/solr-solrj/index.html):

SolrQuery query = new SolrQuery();
...
query.setRequestHandler("/export");
...
httpSolrServer.query(query);

The query now has a parameter &qt=export. It blew up giving me:

org.apache.solr.client.solrj.SolrServerException: Error executing query

More search suggested using SolrRequest instead of SolrQuery, I tried it:

SolrQuery query = new SolrQuery();
...
query.setRequestHandler("/export");
SolrRequest solrRequest = new QueryRequest(query);
httpSolrServer.request(solrRequest);

Now I get:

java.nio.charset.UnsupportedCharsetException: gzip

Any ideas?

---edit---

I found an option in httpSolrServer.request() to add a ResponseParser. I found 4 ResponseParsers. Tried them all, the only one that worked was NoOpResponseParser. Now I have the correct results, but dumped as a plain string in a single entry in a NamedList. I tried to parse it as JSON, but it's not in proper format. Each 30,000 document, there's a missing , !!!!.

I returned back to solrconfig.xml and changed wt in the /export handler from xsort to json. Now the response format has changed, but it's also not in proper format (data is incomplete) !!!!. And XML is not supported.

I'm truly baffled.