[STREAMING][MINOR] Scaladoc + logs

Found while doing code review

Author: Jacek Laskowski <jacek@japila.pl>

Closes #10878 from jaceklaskowski/streaming-scaladoc-logs-tiny-fixes.

streaming/src/main/scala/org/apache/spark/streaming/StateSpec.scala

@@ -30,9 +30,8 @@ import org.apache.spark.util.ClosureCleaner
  * `mapWithState` operation of a
  * [[org.apache.spark.streaming.dstream.PairDStreamFunctions pair DStream]] (Scala) or a
  * [[org.apache.spark.streaming.api.java.JavaPairDStream JavaPairDStream]] (Java).
- * Use the [[org.apache.spark.streaming.StateSpec StateSpec.apply()]] or
- * [[org.apache.spark.streaming.StateSpec StateSpec.create()]] to create instances of
- * this class.
+ * Use [[org.apache.spark.streaming.StateSpec.function() StateSpec.function]] factory methods
+ * to create instances of this class.
  *
  * Example in Scala:
  * {{{

streaming/src/main/scala/org/apache/spark/streaming/dstream/MapWithStateDStream.scala

@@ -90,7 +90,7 @@ private[streaming] class MapWithStateDStreamImpl[
 }
 
 /**
- * A DStream that allows per-key state to be maintains, and arbitrary records to be generated
+ * A DStream that allows per-key state to be maintained, and arbitrary records to be generated
  * based on updates to the state. This is the main DStream that implements the `mapWithState`
  * operation on DStreams.
  *

streaming/src/main/scala/org/apache/spark/streaming/scheduler/ReceivedBlockTracker.scala

@@ -166,7 +166,7 @@ private[streaming] class ReceivedBlockTracker(
   def cleanupOldBatches(cleanupThreshTime: Time, waitForCompletion: Boolean): Unit = synchronized {
     require(cleanupThreshTime.milliseconds < clock.getTimeMillis())
     val timesToCleanup = timeToAllocatedBlocks.keys.filter { _ < cleanupThreshTime }.toSeq
-    logInfo("Deleting batches " + timesToCleanup)
+    logInfo(s"Deleting batches: ${timesToCleanup.mkString(" ")}")
     if (writeToLog(BatchCleanupEvent(timesToCleanup))) {
       timeToAllocatedBlocks --= timesToCleanup
       writeAheadLogOption.foreach(_.clean(cleanupThreshTime.milliseconds, waitForCompletion))

streaming/src/main/scala/org/apache/spark/streaming/ui/StreamingJobProgressListener.scala

@@ -91,7 +91,7 @@ private[streaming] class StreamingJobProgressListener(ssc: StreamingContext)
 
   override def onBatchStarted(batchStarted: StreamingListenerBatchStarted): Unit = synchronized {
     val batchUIData = BatchUIData(batchStarted.batchInfo)
-    runningBatchUIData(batchStarted.batchInfo.batchTime) = BatchUIData(batchStarted.batchInfo)
+    runningBatchUIData(batchStarted.batchInfo.batchTime) = batchUIData
     waitingBatchUIData.remove(batchStarted.batchInfo.batchTime)
 
     totalReceivedRecords += batchUIData.numRecords