public void start(String fileName, List<IApimanLogger> extraLoggers) {
        ArrayList<IApimanLogger> delegates = new ArrayList<>(extraLoggers.size()+1);
        delegates.addAll(extraLoggers);
        delegates.add(logger);
        this.logger = new MultiLogger(delegates);
        start(fileName);
    }
Set an additional logger implementations. 

@see #start(String, IApimanLogger)
manager/api/export-import/src/main/java/io/apiman/manager/api/exportimport/manager/StorageImportDispatcher.java