public String doLayout(ILoggingEvent event) {
        if (!isStarted()) {
            return CoreConstants.EMPTY_STRING;
        }
        return writeLoopOnConverters(event);
    }
@Test
    public void testNopExeptionHandler() {
        pl.setPattern("%nopex %m%n");
        pl.start();
        String val = pl.doLayout(makeLoggingEvent(aMessage, ex));
        assertTrue(!val.contains("java.lang.Exception: Bogus exception"));
    }