private void closeCurrentOutputStream() {
        try {
            LOGGER.debug("Closing output: {}", output);
            output.close();
        } catch (final IOException e) {
            error(e.getMessage(), e);
        } finally {
            output = null;
        }
    }
Method to allow subclasses to insert segment markers between records.
stroom-pipeline/src/main/java/stroom/pipeline/writer/AbstractAppender.java