code: protected void appendDefaultOperator(SolrQuery solrQuery, @Nullable Operator defaultOperator) {
  		if (defaultOperator != null && !Query.Operator.NONE.equals(defaultOperator)) {
  			solrQuery.set("q.op", defaultOperator.asQueryStringRepresentation());
  		}
  	}
docs: Set {@code q.op} parameter for {@link SolrQuery}
  
  @param solrQuery
  @param defaultOperator