public String doLayout(ILoggingEvent event) {
        if (!isStarted()) {
            return CoreConstants.EMPTY_STRING;
        }
        return writeLoopOnConverters(event);
    }
@Test
    public void testWithParenthesis() {
        pl.setPattern("\\(%msg:%msg\\) %msg");
        pl.start();
        LoggingEvent le = makeLoggingEvent(aMessage, null);
        String val = pl.doLayout(le);
        assertEquals("(Some message:Some message) Some message", val);
    }