SQL> select * from dba_sys_privs where grantee = 'PDB_DBA';
GRANTEE PRIVILEGE ADMIN_OPT COMMON
--------------------- ------------------------------ --------- ---------
PDB_DBA SET CONTAINER NO NO
PDB_DBA CREATE PLUGGABLE DATABASE NO NO
PDB_DBA CREATE SESSION NO NO
→サポートいわく、「pdbadminは管理者なのでロックするな」