Changes

#890: added "expiry" to Policy's `Subject` as new type `SujectExpiry`

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: added missing factory methods for creating a Subject with SubjectExpiry

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: enhanced PolicyCommandStrategies in order to "round up" passed in subject expiry
* made the granularity to apply configurable in PolicyConfig
* added unit tests for PolicyCommandStrategies for the affected strategies applying the rounding up of subject expiries
* adjusted the PolicyValidator to make sure that configured subject expiries are not in the past

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: enhanced OpenAPI docs about Policy subject "expiry"
* added "expiry" as well to Policy JsonSchema
* did some cleanup in OpenAPI docs while at it (e.g. moving schemas to subfolders)

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: fixed review findings:
* applied double checked locking in PolicyCommandStrategies
* simplified adjusting a PolicyEntry with adjusted subjects
* fixed that an already pre-"rounded/truncated" subject expiration was rounded up to the next unit where it should not have

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: fixed obsolete synchronized keyword on getInstance()

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: automatically schedule persisting+publishing a DeleteSubject event when
* the next subject will expire
* re-schedule when after the expired subject deletion there are still other subjects to expire
* added tests, fixed etag calculation which must be done based on the adjusted command (e.g. with rounded up expiry timestamp)

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: fixed time based unit tests which did not handle timezones correctly

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: schedule expiry cleanup also after snapshot recovery
* added unit test for correct expiration after actor restart/recovery

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: adjusted @since javadoc annotations to 2.0.0

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: invalidate policy enforcer caches in concierge whenever the PolicyPersistenceActor publishes a PolicyTag message
* this PolicyTag message is published when an in the concierge processed PolicyCommand did not result already in a cache validation
* as a result, the "DeleteSubject" event which is created in the background by the expiry feature will cause the concierge policy enforcer cache to invalidate

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: fixed and enhanced unit tests after invalidate policy enforcer caches in concierge whenever the PolicyPersistenceActor publishes a PolicyTag message

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

[#890] review: add missing word "active" to expiry description; fix broken link in cloudevent openapi.

Signed-off-by: Yufei Cai <yufei.cai@bosch.io>

[#890] review: remove unnecessary conditional; test chained expiry; add TODO.

Signed-off-by: Yufei Cai <yufei.cai@bosch.io>

[#890] suppress acknowledgement from akka pubsub logged as warning.

Signed-off-by: Yufei Cai <yufei.cai@bosch.io>

[#890] Fix off-by-1 error in revision of scheduled SubjectDeleted events; optimize PolicyEventForwarder to not query database in the absence of policy changes.

Signed-off-by: Yufei Cai <yufei.cai@bosch.io>

[#890] Ignore expiring subjects in policies validator; fix PolicyCommandEnforcementTest.

Signed-off-by: Yufei Cai <yufei.cai@bosch.io>

[#890] Fix ModifyPolicyEntryStrategyTest and ModifySubjectsStrategyTest.

Signed-off-by: Yufei Cai <yufei.cai@bosch.io>

fixed compile error after merge from master

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: added documentation about policy subject expiry

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: fix findings:
* return status code 400 instead of 403 when trying to use an expiry TS from the past
* ensure that a recovery first removes expired subjects before applying further commands
* cope with expiry timestamps in a distant future (>8 months from now) as those caused long-overflow exceptions: reschedule checking after 1 day in such cases

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: fix review findings of fixing findings:
* simplified scheduling of next expiry check
* added missing javadoc
* deduplicated scheduling

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

#890: fix review findings of fixing findings:
* further simplified scheduling of next expiry check
* added unit test ensuring that an already expired subject is deleted during persistence recovery

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

increase maxStackDepth to 25 in order to support basic protobuf experiments

Signed-off-by: Thomas Jaeckle <thomas.jaeckle@bosch.io>

[#890] Review: PolicyPersistenceActorTest.ensureSubjectExpiryIsCleanedUpAfterRecovery

- Kill the persistence actor right away, so that it has no chance
  to delete the expired subject before termination

- Test the persistence actor in a shard region in order for
  SudoRetrievePolicy to be the first message the actor processes
  when restored.

Signed-off-by: Yufei Cai <yufei.cai@bosch.io>