Use linkedHashMap to preserve the order of partitions while processing RemoteFetch requests.

Author: kamalcph

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

@@ -1636,7 +1636,7 @@ class ReplicaManager(val config: KafkaConfig,
   /**
    * Process all remote fetches by creating async read tasks and handling them in DelayedRemoteFetch collectively.
    */
-  private def processRemoteFetches(remoteFetchInfos: util.HashMap[TopicIdPartition, RemoteStorageFetchInfo],
+  private def processRemoteFetches(remoteFetchInfos: util.LinkedHashMap[TopicIdPartition, RemoteStorageFetchInfo],
                                    params: FetchParams,
                                    responseCallback: Seq[(TopicIdPartition, FetchPartitionData)] => Unit,
                                    logReadResults: Seq[(TopicIdPartition, LogReadResult)],
@@ -1675,7 +1675,7 @@ class ReplicaManager(val config: KafkaConfig,
     var errorReadingData = false
 
     // topic-partitions that have to be read from remote storage
-    val remoteFetchInfos = new util.HashMap[TopicIdPartition, RemoteStorageFetchInfo]()
+    val remoteFetchInfos = new util.LinkedHashMap[TopicIdPartition, RemoteStorageFetchInfo]()
 
     var hasDivergingEpoch = false
     var hasPreferredReadReplica = false