Fix issues missed by checkstyle

Fix issues missed by checkstyle

- Added a module in our checkstyle config to check for unused variable
  (very surprised this was never there)
- the missing finals in ProvMnSException were a false positive since there was a @NoArgsContructor
  (surprised Sonar didnt realize that)
- it was still a code smell though and I refactored the code so we didn't need the allArgsConstructor anymore (nor setters)
- also fixed valid warning on access level noArgsCosntructor (checkstyle never caught those before so that's ok)

Issue-ID: CPS-3128
Change-Id: I6acc5bd9bc6bd18f30a346e8049ce6ee456c580a
Signed-off-by: ToineSiebelink <toine.siebelink@est.tech>