@PipelineProperty(description = "Provide a cron expression to determine when files are rolled.",
            displayPriority = 5)
    public void setSchedule(final String expression) {
        super.setSchedule(expression);
    }
Parses a POSIX-style file permission string like "rwxr--r--"
stroom-pipeline/src/main/java/stroom/pipeline/writer/RollingFileAppender.java