SolrQuery::addMltQueryField Maps to mlt.qf &reftitle.description; public SolrQuerySolrQuery::addMltQueryField stringfield floatboost Maps to mlt.qf. It is used to specify query fields and their boosts &reftitle.parameters; field The name of the field boost Its boost value &reftitle.returnvalues; Returns the current SolrQuery object, if the return value is used.