#vulnerable code 
                                @Test
    public void testThresholds() {
        final ThresholdFilter filter = ThresholdFilter.createFilter("ERROR", null, null);
        filter.start();
        assertTrue(filter.isStarted());
        assertSame(Filter.Result.DENY, filter.filter(null, Level.DEBUG, null, null, (Throwable) null));
        assertSame(Filter.Result.NEUTRAL, filter.filter(null, Level.ERROR, null, null, (Throwable) null));
        LogEvent event = new Log4jLogEvent(null, null, null, Level.DEBUG, new SimpleMessage("Test"), null);
        assertSame(Filter.Result.DENY, filter.filter(event));
        event = new Log4jLogEvent(null, null, null, Level.ERROR, new SimpleMessage("Test"), null);
        assertSame(Filter.Result.NEUTRAL, filter.filter(event));
    } 
                            #location 8 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Test
    public void testThresholds() {
        final ThresholdFilter filter = ThresholdFilter.createFilter(Level.ERROR, null, null);
        filter.start();
        assertTrue(filter.isStarted());
        assertSame(Filter.Result.DENY, filter.filter(null, Level.DEBUG, null, null, (Throwable) null));
        assertSame(Filter.Result.NEUTRAL, filter.filter(null, Level.ERROR, null, null, (Throwable) null));
        LogEvent event = new Log4jLogEvent(null, null, null, Level.DEBUG, new SimpleMessage("Test"), null);
        assertSame(Filter.Result.DENY, filter.filter(event));
        event = new Log4jLogEvent(null, null, null, Level.ERROR, new SimpleMessage("Test"), null);
        assertSame(Filter.Result.NEUTRAL, filter.filter(event));
    }