Forcing POST when SPARQLing an endpoint.

[Olivier Rossel]

I use such a code to query SPARQL endpoints:

String service = "url of endpoint";
String queryString = "a select query"
ByteArrayOutputStream os = new ByteArrayOutputStream();
QueryExecution qexec = new QueryEngineHTTP(service, queryString);
Model m = qexec.execConstruct();
m.write(os, "RDF/XML");

I need now to force the HTTP request to send its data via POST, instead of GET.

How can I do that?

Note: it seems that the HTTP connection management
in QueryEngineHTTP is private, so I cannot reach it from my code.
Any help is welcome.