pom: enforce utf8 for source files

as we have some non-ASCII strings in the code

Acked-by: Gerd Behrmann
Target: master
nfs: reject readdir requests if cached listing not found

readdir operation expects nfs server to keep a snapshot
of directory listing and uses verifier as an snapshot
identifier.

Reject requests if we can't find a valid snapshot and
force client to start over.

Acked-by:
Target: master