Merging of all PDBs of CDBs into Single CDB

1) Merge all PDBs of cdb1 into cdb2
2) Drop cdb1

[oracle@myorasrv ~]$ . oraenv
ORACLE_SID = [cbd1] ? cdb1

[oracle@myorasrv ~]$ sqlplus / as sysdba

SQL> select name,open_mode from v$pdbs;

NAME                   OPEN_MODE
------------------------------ ----------
PDB$SEED               READ ONLY
PDB1_1                   READ WRITE

SQL> alter pluggable database pdb1_1 close immediate;

Pluggable database altered.

SQL> alter pluggable database pdb1_1 unplug into 'xmlPDB1_1.xml';

Pluggable database altered.

SQL> col PDB_NAME for a20
SQL> select pdb_name,status from cdb_PDBS
  2  where pdb_name='PDB1_1';

PDB_NAME         STATUS
-------------------- ---------
PDB1_1             UNPLUGGED

SQL> drop pluggable database pdb1_1 keep datafiles;

Pluggable database dropped.

SQL> exit

[oracle@myorasrv CDB]$ . oraenv
ORACLE_SID = [cdb1] ? cdb2
The Oracle base for ORACLE_HOME=/u01/app/oracle/product/12.1.0/dbhome_1 is /u01/app/oracle
[oracle@myorasrv CDB]$ sqlplus / as sysdba

SQL> !cat compat.sql 
set serveroutput on
DECLARE
  compat BOOLEAN := FALSE;
  BEGIN
  compat := DBMS_PDB.CHECK_PLUG_COMPATIBILITY( 
  pdb_descr_file => '/u01/app/oracle/product/12.1.0/dbhome_1/dbs/xmlPDB1_1.xml', pdb_name => 'pdb1_1');
  if compat then
  DBMS_OUTPUT.PUT_LINE('Is pluggable compatible? YES');
  else DBMS_OUTPUT.PUT_LINE('Is pluggable compatible? NO');
  end if;
end;
/

SQL> @compat.sql
Is pluggable compatible? YES

PL/SQL procedure successfully completed.

SQL> create pluggable database pdb1_1 using 'xmlPDB1_1.xml' nocopy;

Pluggable database created.

SQL> alter pluggable database pdb1_1 open;

Pluggable database altered.

SQL> select name,open_mode from v$pdbs;

NAME                   OPEN_MODE
------------------------------ ----------
PDB$SEED               READ ONLY
PDB2_1                   READ ONLY
PDB2_2                   READ WRITE
PDB_ORCL2               READ WRITE
PDB1_1                   READ WRITE

SQL> exit

[oracle@myorasrv CDB]$ . oraenv
ORACLE_SID = [cdb2] ? cdb1
The Oracle base for ORACLE_HOME=/u01/app/oracle/product/12.1.0/dbhome_1 is /u01/app/oracle
[oracle@myorasrv CDB]$ sqlplus / as sysdba

SQL> shutdown immediate
SQL> startup mount restrict;
SQL> drop database;

Database dropped.