public Map<K, V> getMapSortByKeyDown(Map<K, V> sourceMap) {
        return sortByKey(sourceMap, GROW_DOWN);
    }
public Map<K, V> getMapSortByKeyDown(Map<K, V> sourceMap) {
        return sortByKey(sourceMap, GROW_DOWN);
    }
public Map < K , V > getMapSortByKeyDown ( Map < K , V > sourceMap ) { return sortByKey ( sourceMap , GROW_DOWN ) ; }
按照Map中value进行降序排列

@param sourceMap
要排序 map
@return 排序后 map
按照Map中value进行降序排列