In 12.2 new listener services

In 12.2 a new feature is introduced in listener called Proxy PDB services.

This is a special in-memory service used for communicating with remote PDB for features such as PROXY PDB.  A Proxy PDB creates such a GUID service to the source PDB , and then issues query over dblink connected using this GUID service name. Users do not need to use the GUID service, it is for internal use only. These service will be created automatically while creating pdb's , it can’t be dropped and it can viewed in SQL> select NAME,GUID from v$pdbs;

This Proxy PDB will helping in reloacate a PDB to a different server or data centre.