Async, non-blocking Solr Server that just allows to #query(SolrQuery).
Subclass of SolrException that allows us to capture an arbitrary HTTP status code that may have been returned by the remote server or a proxy along the way.
Async, non-blocking Solr Server that just allows to
#query(SolrQuery). The usage shall be similar to the solrj SolrServer, so query returns a future of aQueryResponse.