public StdOutVisitorHandler.OutputFormat stdOutHandlerOutputFormat() {
            if (jsonLinesOutput) {
                return StdOutVisitorHandler.OutputFormat.JSONL;
            } else if (jsonOutput) {
                return StdOutVisitorHandler.OutputFormat.JSON;
            } else {
                return StdOutVisitorHandler.OutputFormat.XML;
            }
        }
If not specified in options, will get form cluster list
vespaclient-java/src/main/java/com/yahoo/vespavisit/VdsVisit.java