CLONE - [CMT][BUG] Migrated FK from Mysql to CUBRID, if one table has primary key, the FK will became index

1 Create tables in mysql
create table fksn1 (id nchar(10));
create table fksnmain1 (id nchar(10));
alter table fksnmain1 add constraint primary key(id);
alter table fksn1 add constraint fk_fsn1_fsn1 foreign key(id) references fksnmain1(id) on update cascade on delete cascade;
2 Do migration

Actual result:
The FK became index.

Addtional
If the test cases is as follows, it's ok.
1 create table in mysql.
create table fksn2 (id nchar(10));
create table fksnmain2 (id nchar(10));
alter table fksnmain2 add constraint primary key(id);
alter table fksn2 add constraint primary key(id);
alter table fksn2 add constraint fk_fsn2_fsn2 foreign key(id) references fksnmain2(id) on update cascade on delete cascade;
2 Do migration.