MINOR: A few cleanups in BrokerToControllerChannelManager (#11937)

Make the code style more consistent

Reviewers: Luke Chen <showuon@gmail.com>

core/src/main/scala/kafka/server/BrokerToControllerChannelManager.scala

@@ -78,9 +78,11 @@ class MetadataCacheControllerNodeProvider(
 }
 
 object RaftControllerNodeProvider {
-  def apply(raftManager: RaftManager[ApiMessageAndVersion],
+  def apply(
+    raftManager: RaftManager[ApiMessageAndVersion],
     config: KafkaConfig,
-            controllerQuorumVoterNodes: Seq[Node]): RaftControllerNodeProvider = {
+    controllerQuorumVoterNodes: Seq[Node]
+  ): RaftControllerNodeProvider = {
     val controllerListenerName = new ListenerName(config.controllerListenerNames.head)
     val controllerSecurityProtocol = config.effectiveListenerSecurityProtocolMap.getOrElse(controllerListenerName, SecurityProtocol.forName(controllerListenerName.value()))
     val controllerSaslMechanism = config.saslMechanismControllerProtocol
@@ -98,7 +100,8 @@ object RaftControllerNodeProvider {
  * Finds the controller node by checking the metadata log manager.
  * This provider is used when we are using a Raft-based metadata quorum.
  */
-class RaftControllerNodeProvider(val raftManager: RaftManager[ApiMessageAndVersion],
+class RaftControllerNodeProvider(
+  val raftManager: RaftManager[ApiMessageAndVersion],
   controllerQuorumVoterNodes: Seq[Node],
   val listenerName: ListenerName,
   val securityProtocol: SecurityProtocol,
@@ -133,7 +136,6 @@ object BrokerToControllerChannelManager {
   }
 }
 
-
 trait BrokerToControllerChannelManager {
   def start(): Unit
   def shutdown(): Unit
@@ -144,7 +146,6 @@ trait BrokerToControllerChannelManager {
   ): Unit
 }
 
-
 /**
  * This class manages the connection between a broker and the controller. It runs a single
  * [[BrokerToControllerRequestThread]] which uses the broker's metadata cache as its own metadata to find
@@ -250,13 +251,14 @@ class BrokerToControllerChannelManagerImpl(
     ))
   }
 
-  def controllerApiVersions(): Option[NodeApiVersions] =
+  def controllerApiVersions(): Option[NodeApiVersions] = {
-    requestThread.activeControllerAddress().flatMap(
+    requestThread.activeControllerAddress().flatMap { activeController =>
-      activeController => if (activeController.id() == config.brokerId)
+      if (activeController.id == config.brokerId)
         Some(currentNodeApiVersions)
       else
-        Option(apiVersions.get(activeController.idString()))
+        Option(apiVersions.get(activeController.idString))
-  )
+    }
+  }
 }
 
 abstract class ControllerRequestCompletionHandler extends RequestCompletionHandler {
@@ -351,10 +353,10 @@ class BrokerToControllerRequestThread(
       requestQueue.putFirst(queueItem)
     } else if (response.responseBody().errorCounts().containsKey(Errors.NOT_CONTROLLER)) {
       // just close the controller connection and wait for metadata cache update in doWork
-      activeControllerAddress().foreach { controllerAddress => {
+      activeControllerAddress().foreach { controllerAddress =>
         networkClient.disconnect(controllerAddress.idString)
         updateControllerAddress(null)
-      }}
+      }
 
       requestQueue.putFirst(queueItem)
     } else {