public String doLayout(ILoggingEvent event) {
        if (!isStarted()) {
            return CoreConstants.EMPTY_STRING;
        }
        return writeLoopOnConverters(event);
    }
@Test
    public void testCompositePattern() {
        pl.setPattern("%-56(%d %lo{20}) - %m%n");
        pl.start();
        String val = pl.doLayout(getEventObject());
        // 2008-03-18 21:55:54,250 c.q.l.c.pattern.ConverterTest - Some message
        String regex = ISO_REGEX + " c.q.l.c.p.ConverterTest          - Some message\\s*";
        assertTrue(val.matches(regex));
    }