@Override
    public void onMetaDataChanged(final List<MetaData> changed, final DataEventTypeEnum eventType) {
        if (CollectionUtils.isEmpty(changed)) {
            return;
        }
        this.updateMetaDataCache();
        this.afterMetaDataChanged(changed, eventType);
    }
@Test
    public void testOnMetaDataChanged() {
        List<MetaData> empty = Lists.newArrayList();
        DataEventTypeEnum eventType = mock(DataEventTypeEnum.class);
        listener.onMetaDataChanged(empty, eventType);
        assertFalse(listener.getCache().containsKey(ConfigGroupEnum.META_DATA.name()));
        List<MetaData> metaDatas = Lists.newArrayList(mock(MetaData.class));
        listener.onMetaDataChanged(metaDatas, eventType);
        assertTrue(listener.getCache().containsKey(ConfigGroupEnum.META_DATA.name()));
    }