public String doLayout(ILoggingEvent event) {
        if (!isStarted()) {
            return CoreConstants.EMPTY_STRING;
        }
        return writeLoopOnConverters(event);
    }
@Test
    public void contextProperty() {
        pl.setPattern("%property{a}");
        pl.start();
        loggerContext.putProperty("a", "b");

        String val = pl.doLayout(getEventObject());
        assertEquals("b", val);
    }