Cannot Select Individual Kafka Connect Cluster for the KafkaConnectRestartConnectors Action

[aaronmillerbraze]

Describe the bug
When trying to restart connectors for a specific Kafka Connect cluster, there is a java.lang.ClassCastException error message that gets thrown.

To Reproduce
Try to restart a connector in a specific connect cluster with this command:

$ jikkou action KafkaConnectRestartConnectors execute --connect-cluster=example-connect-cluster

This is the output after trying to restart connectors while specifying a connect cluster:

$ jikkou action KafkaConnectRestartConnectors execute --connect-cluster=example-connect-cluster                                                                   17:03:16
java.lang.ClassCastException: java.lang.String cannot be cast to java.util.List
        at java.base@21.0.2/java.util.Optional.map(Optional.java:260)
        at io.streamthoughts.jikkou.kafka.connect.action.KafkaConnectRestartConnectorsAction.getConnectClusters(KafkaConnectRestartConnectorsAction.java:267)
        at io.streamthoughts.jikkou.kafka.connect.action.KafkaConnectRestartConnectorsAction.execute(KafkaConnectRestartConnectorsAction.java:133)
        at io.streamthoughts.jikkou.core.DefaultApi.execute(DefaultApi.java:465)
        at io.streamthoughts.jikkou.client.command.action.ExecuteActionCommand.call(ExecuteActionCommand.java:56)
        at io.streamthoughts.jikkou.client.command.action.ExecuteActionCommand.call(ExecuteActionCommand.java:20)
        at picocli.CommandLine.executeUserObject(CommandLine.java:2045)
        at picocli.CommandLine.access$1500(CommandLine.java:148)
        at picocli.CommandLine$RunLast.executeUserObjectOfLastSubcommandWithSameParent(CommandLine.java:2465)
        at picocli.CommandLine$RunLast.handle(CommandLine.java:2457)
        at picocli.CommandLine$RunLast.handle(CommandLine.java:2419)
        at picocli.CommandLine$AbstractParseResultHandler.execute(CommandLine.java:2277)
        at picocli.CommandLine$RunLast.execute(CommandLine.java:2421)
        at io.streamthoughts.jikkou.client.Jikkou.executionStrategy(Jikkou.java:150)
        at picocli.CommandLine.execute(CommandLine.java:2174)
        at io.streamthoughts.jikkou.client.Jikkou.execute(Jikkou.java:140)
        at io.streamthoughts.jikkou.client.Jikkou.main(Jikkou.java:128)
        at java.base@21.0.2/java.lang.invoke.LambdaForm$DMH/sa346b79c.invokeStaticInit(LambdaForm$DMH)

Error: ClassCastException: java.lang.String cannot be cast to java.util.List

Expected behavior
An output such that connectors have been restarted. Here is an example of a successful restart without specifying a connect cluster:

$ jikkou action KafkaConnectRestartConnectors execute
---
kind: "ApiActionResultSet"
apiVersion: "core.jikkou.io/v1"
metadata:
  labels: {}
  annotations: {}
results:
- status: "SUCCEEDED"
  data:
    apiVersion: "kafka.jikkou.io/v1beta1"
    kind: "KafkaConnector"
    metadata:
      name: "example-connector"
      labels:
        kafka.jikkou.io/connect-cluster: "example-connect-cluster"
      annotations: {}
    spec:
      connectorClass: "io.confluent.connect.http.HttpSinkConnector"
      tasksMax: 1
      config:
        confluent.topic.bootstrap.servers: "<redacted>:9092"
        topics: "example-topic"
        http.api.url: "http://localhost"
        reporter.bootstrap.servers: "<redacted>:9092"
      state: "RUNNING"
    status:
      connectorStatus:
        name: "example-connector"
        connector:
          state: "RUNNING"
          worker_id: "<redacted>:8083"
        tasks:
        - id: 0
          state: "RUNNING"
          worker_id: "<redacted>:8083"

Runtime environment

• OS: macOS Sonoma 14.1.1
• Jikkou: 0.35.7
• Kafka Cluster Version: cp-7.3.1

Additional context
When not specifying a connect cluster, Jikkou runs through all of the clusters listed in our config file to restart connectors successfully, but does not work when specifying a specific connect cluster.