@PipelineProperty(description = "Choose how frequently files are rolled.",
            defaultValue = "1h",
            displayPriority = 4)
    public void setFrequency(final String frequency) {
        super.setFrequency(frequency);
    }
Parses a POSIX-style file permission string like "rwxr--r--"
stroom-pipeline/src/main/java/stroom/pipeline/writer/RollingFileAppender.java