Fix compile warnings in mantis-control-plane-server

[itsharis]

Context

Progress towards: [#392]

• Remove deprecated bindAndHandle
• Remove deprecated Mockito.Matchers and replace with ArgumentMatchers
• Remove deprecated ActorMaterializer and replace with Materializer
• Remove deprecated startPeriodicTimer and replace with startTimerAtFixedRate
• Fix serialization of Optional in unit tests
• Replace DatatypeConverter with BaseEncoding

Checklist

• ./gradlew build compiles code correctly
• Added new tests where applicable
• ./gradlew test passes all tests
• Extended README or added javadocs where applicable

Note: There are more fixes for for this module, however but i am splitting them up so they are in a more consumable format

[Andyz26]

I don't think it's a good idea to use the Flink-shaded version of guava. There is a mantis-shaded version.

[itsharis]

Thanks i will make this change.

[Andyz26]

where and why is this "empty" key introduced?

[itsharis]

Had to do some digging into this.

This is a difference with jakson on JDK 8 vs JDK 11 (JDK i am using on M1: https://adoptium.net/download/).
I thought setting the (inteliJ IDEA) File -> Project Structure- > Language level to 8 would be sufficient, however it dosent seem that way.
JDK 8 evaluates:
objectMapper.writeValueAsString(Optional.empty()) as {"present":false}
JDK 11 evaluates:
objectMapper.writeValueAsString(Optional.empty()) as {empty":true,"present":false}

Similarly:
objectMapper.writeValueAsString(Optional.of("test")) evaluates to {"empty":false,"present":true}
I will undo this change since sourceCompatibility is set Java 8

[github-actions]

Test Results

  82 files   -   44    82 suites   - 44   2m 9s ⏱️ - 4m 7s
416 tests  - 119  406 ✔️  - 120  7 💤  - 1  3 ❌ +2 
416 runs   - 120  406 ✔️  - 121  7 💤  - 1  3 ❌ +2 

For more details on these failures, see this check.

Results for commit 9e754ac. ± Comparison against base commit 6fc313e.

This pull request removes 119 tests.

io.mantisrx.publish.AbstractSubscriptionTrackerTest ‑ testDefaultStreamKeyAsStreamName()
io.mantisrx.publish.AbstractSubscriptionTrackerTest ‑ testDiscardSubscriptionsBeyondMax()
io.mantisrx.publish.AbstractSubscriptionTrackerTest ‑ testMaxSubscriptionCountChange()
io.mantisrx.publish.AbstractSubscriptionTrackerTest ‑ testSubscriptionUpdate()
io.mantisrx.publish.AbstractSubscriptionTrackerTest ‑ testUpdateMultipleStreams()
io.mantisrx.publish.AbstractSubscriptionTrackerTest ‑ testUpdateMultipleStreamsWithUnionSubscriptions()
io.mantisrx.publish.DefaultSubscriptionTrackerTest ‑ testSubsNotRefreshOnNoRegisteredStreams()
io.mantisrx.publish.DefaultSubscriptionTrackerTest ‑ testSubscriptionsFetchFailureHandling()
io.mantisrx.publish.DefaultSubscriptionTrackerTest ‑ testSubscriptionsResolveToMajorityAmongWorkers()
io.mantisrx.publish.EventDrainerTest ‑ shouldDrainAndNoopForNonexistentSubscribers()
…

[Andyz26]

@itsharis please rebase to latest master and get a clean CI run.

[itsharis]

Not sure if this was the right approach:
i synced the repo via github web UI, and synced my forked branch with master.

If not, please advise what is the best way to do this.