KNOX-2578 - TokenResource logging token UUIDs

[pzampino]

What changes were proposed in this pull request?

Replace the logging of Knox token UUIDs in TokenResource with masked representations which are safe to present in logs.

How was this patch tested?

mvn -Ppackage,release clean install

1. Installed the gateway and enabled DEBUG logging.
2. Deployed the KNOXTOKEN service with server-managed state enabled.
3. Deployed a topology with the JWTProvider (server-managed state enabled) and WEBHDFS.
4. Requested a token.
5. curl -ivku Token:$TOKEN "https://localhost:8443/gateway/pz-demo/webhdfs/v1/?op=LISTSTATUS"
6. curl -ivku Passcode:$PASSCODE "https://localhost:8443/gateway/pz-demo/webhdfs/v1/tmp?op=LISTSTATUS"
7. Performed the same with invalid token/passcode (to verify UnknownTokenException contents).
8. Grepped the logs for (\S){8}-(\S){4}-(\S){4}-(\S){4}-(\S){12} - confirmed no matches
9. Grepped the logs for (\S){8}.{3}(\S){12} - confirmed matches

[smolnar82]

LGTM
Thanks for the detailed testing information.
I also went thru on that class locally and it seems these were the only remaining logs.

[moresandeep]

Looks good!