udfarrayexclude doesn't work

[wangyunpeng666]

First execute command on hive cli:
CREATE TEMPORARY FUNCTION udfarrayexclude AS 'com.facebook.hive.udf.UDFArrayExclude';
SELECT udfarrayexclude(array(1,2,3),array(1,2))

The result is as follows:
hive> SELECT udfarrayexclude(array(1,2,3),array(1,2));
OK
[1,2,3]
Time taken: 4.858 seconds, Fetched: 1 row(s)

why? In my opinion, the result should be [3]

Could someone give me some help?