public String getValue(Event event) {
        if (value != null) {
            return value;
        } else if (templateBuilder != null) {
            return (String) templateBuilder.build(event);
        } else if (dataIndex != -1) {
            return String.valueOf(event.getData(dataIndex));
        } else {
            return null;
        }
    }
Holder class for general transport options.
modules/siddhi-core/src/main/java/io/siddhi/core/util/transport/Option.java