private SearchSourceBuilder parseSearchSource(RestRequest request) {
SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
String queryString = request.param("q");
if (queryString != null) {
QueryStringQueryBuilder queryBuilder = QueryBuilders.queryString(queryString);
queryBuilder.defaultField(request.param("df"));
queryBuilder.analyzer(request.param("analyzer"));
queryBuilder.analyzeWildcard(request.paramAsBoolean("analyze_wildcard", false));
queryBuilder.lowercaseExpandedTerms(request.paramAsBoolean("lowercase_expanded_terms", true));
String defaultOperator = request.param("default_operator");
if (defaultOperator != null) {