DBMS_METADATA.GET_SXML_DDL may produce incorrect DDL for trigger in EBR environment

I have recently discovered a case when DBMS_METADATA.GET_SXML_DDL returns incorrect DDL for the trigger in an EBR environment.
Here is a test case to reproduce the issue that is present in 12.1.0.2.170117 and 11.2.0.4.161018:

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SQL> grant connect, create table, create view, create trigger to tc identified by tc;   Grant succeeded.   SQL> SQL> alter user tc enable editions for view,trigger;   User altered.   SQL> SQL> conn tc/tc Connected. SQL> SQL> create table t (   2    x int)   3  /   Table created.   SQL> SQL> create or replace editioning view ev   2  as   3  select *   4    from t   5  /   View created.   SQL> SQL> create or replace trigger trg   2  before update of x on ev   3  declare   4  begin   5    null;   6  end;   7  /   Trigger created.

Let us look at the DDL of the trigger returning by DBMS_METADATA.GET_DDL and DBMS_METADATA.GET_SXML_DDL functions.

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SQL> select dbms_metadata.get_ddl( 'TRIGGER', 'TRG') from dual;   DBMS_METADATA.GET_DDL('TRIGGER','TRG') --------------------------------------------------------------------------------     CREATE OR REPLACE EDITIONABLE TRIGGER "TC"."TRG" before update of x on ev declare begin   null; end; ALTER TRIGGER "TC"."TRG" ENABLE     SQL> select dbms_metadata.get_sxml_ddl( 'TRIGGER', 'TRG') from dual;   DBMS_METADATA.GET_SXML_DDL('TRIGGER','TRG') --------------------------------------------------------------------------------   CREATE OR REPLACE TRIGGER "TC"."TRG"   BEFORE UPDATE OF X ON "TC"."EV"   declare begin   null; end;

They are pretty much the same. Now I change the status of my trigger. Please note the highlighted lines showing the differences:

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SQL> alter trigger trg enable;   Trigger altered.   SQL> SQL> select dbms_metadata.get_ddl( 'TRIGGER', 'TRG') from dual;   DBMS_METADATA.GET_DDL('TRIGGER','TRG') --------------------------------------------------------------------------------     CREATE OR REPLACE EDITIONABLE TRIGGER "TC"."TRG" before update of x on ev declare begin   null; end; ALTER TRIGGER "TC"."TRG" ENABLE     SQL> select dbms_metadata.get_sxml_ddl( 'TRIGGER', 'TRG') from dual;   DBMS_METADATA.GET_SXML_DDL('TRIGGER','TRG') --------------------------------------------------------------------------------   CREATE OR REPLACE TRIGGER "TC"."TRG"   BEFORE UPDATE OF X, X ON "TC"."EV"   declare begin   null; end;

I have ended up with two X columns in the output of DBMS_METADATA.GET_SXML_DDL, which is, in fact, a non-working DDL statement.
I played more with this issue and I have eventually obtained four X columns and it is not a limit:

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SQL> alter trigger trg disable;   Trigger altered.   SQL> SQL> select dbms_metadata.get_ddl( 'TRIGGER', 'TRG') from dual;   DBMS_METADATA.GET_DDL('TRIGGER','TRG') --------------------------------------------------------------------------------     CREATE OR REPLACE EDITIONABLE TRIGGER "TC"."TRG" before update of x on ev declare begin   null; end; ALTER TRIGGER "TC"."TRG" DISABLE     SQL> select dbms_metadata.get_sxml_ddl( 'TRIGGER', 'TRG') from dual;   DBMS_METADATA.GET_SXML_DDL('TRIGGER','TRG') --------------------------------------------------------------------------------   CREATE OR REPLACE TRIGGER "TC"."TRG"   BEFORE UPDATE OF X, X, X ON "TC"."EV"   declare begin   null; end;   ALTER TRIGGER "TC"."TRG" DISABLE     SQL> SQL> alter trigger trg enable;   Trigger altered.   SQL> SQL> select dbms_metadata.get_ddl( 'TRIGGER', 'TRG') from dual;   DBMS_METADATA.GET_DDL('TRIGGER','TRG') --------------------------------------------------------------------------------     CREATE OR REPLACE EDITIONABLE TRIGGER "TC"."TRG" before update of x on ev declare begin   null; end; ALTER TRIGGER "TC"."TRG" ENABLE     SQL> select dbms_metadata.get_sxml_ddl( 'TRIGGER', 'TRG') from dual;   DBMS_METADATA.GET_SXML_DDL('TRIGGER','TRG') --------------------------------------------------------------------------------   CREATE OR REPLACE TRIGGER "TC"."TRG"   BEFORE UPDATE OF X, X, X, X ON "TC"."EV"   declare begin   null; end;

The DBMS_METADATA.GET_SXML_DDL procedure uses a SELECT statement similar to the above to obtain the DDL:

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SELECT /*+all_rows*/        SYS_XMLGEN(          VALUE(KU$),          XMLFORMAT.createFormat2('TRIGGER_T', '7')),        KU$.OBJ_NUM   FROM SYS.KU$_TRIGGER_VIEW KU$  WHERE NOT (KU$.BASE_OBJ IS NOT NULL AND BITAND(KU$.BASE_OBJ.FLAGS,128)!=0)    AND KU$.SCHEMA_OBJ.NAME = 'TRG'    AND KU$.SCHEMA_OBJ.OWNER_NAME = 'TC';

The column list for the trigger comes from this part of the SYS.KU$_TRIGGER_VIEW view:

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cast(multiset(select * from ku$_triggercol_view tv               where tv.obj_num=t.obj#             ) as ku$_triggercol_list_t    ),

The code of the KU$_TRIGGERCOL_VIEW view is:

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CREATE OR REPLACE FORCE NONEDITIONABLE VIEW "SYS"."KU$_TRIGGERCOL_VIEW" OF "SYS"."KU$_TRIGGERCOL_T"   WITH OBJECT IDENTIFIER (obj_num,intcol_num,type_num) AS   select '1','0',          tc.obj#, tc.col#, tc.type#, tc.position#, tc.intcol#, c.name,          (select a.name from attrcol$ a where                         a.obj#=tc.obj# and a.intcol#=tc.intcol#)   from col$ c, triggercol$ tc, trigger$ t   where tc.obj#=t.obj#     and c.obj#=t.baseobject     and c.intcol#=tc.intcol#

And the final part of the puzzle is the TRIGGERCOL$ table:

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SQL> select * from sys.triggercol$ where obj#=(select object_id from dba_objects where owner='TC' and object_name='TRG');         OBJ#       COL#      TYPE#  POSITION#    INTCOL# ---------- ---------- ---------- ---------- ----------     214352          1          0          0          1     214352          1          0          0          1     214352          1          0          0          1     214352          1          0          0          1     214352          1       1024          0          1

It gets one row each time I execute the "ALTER TRIGGER ENABLE/DISABLE" statement. I think Oracle Developers should filter the rows because there is only one row with TYPE#=1024.
DBMS_METADATA.GET_DDL returns correct DDL and it seems to be come from the DDL passed by a user.
Conversely, DBMS_METADATA.GET_SXML_DDL tries to reconstruct the user's DDL and it messes things up.