findbugs: Unwritten public fields

its mainly events or handlers that use by UI,
assigned null instead of adding to ignore list

findbugs reason:
UwF: Unwritten public or protected field (UWF_UNWRITTEN_PUBLIC_OR_PROTECTED_FIELD)

Change-Id: I8a8872dd0eb76ae0e4d92af54acec2807f6a1b64
Signed-off-by: Shahar Havivi <shavivi@redhat.com>