I have a running 12c RAC with one CDB and multitenant PDB's. I setup APEX 4.2.4.00.08 in the CDB and not in the PDB's
I setup the APEX LISTENER 2.0.5 with glassfish integration.
I can connect to the normal CDB$ROOT... without any problem.
On page 4 it is shown that you can access the pdbs by only adding the name of the pdb behind the apex url ... ( No further actions required ! )h
I tried it but i always get 404 ERROR ...