Review feedback

Author: Andrew Or

external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeUtils.scala

@@ -60,7 +60,10 @@ object FlumeUtils {
       storageLevel: StorageLevel,
       enableDecompression: Boolean
     ): ReceiverInputDStream[SparkFlumeEvent] = {
-    new FlumeInputDStream[SparkFlumeEvent](ssc, hostname, port, storageLevel, enableDecompression)
+    val inputStream = new FlumeInputDStream[SparkFlumeEvent](
+        ssc, hostname, port, storageLevel, enableDecompression)
+
+    inputStream
   }
 
   /**

external/mqtt/src/main/scala/org/apache/spark/streaming/mqtt/MQTTUtils.scala

@@ -21,8 +21,8 @@ import scala.reflect.ClassTag
 
 import org.apache.spark.storage.StorageLevel
 import org.apache.spark.streaming.StreamingContext
-import org.apache.spark.streaming.api.java.{JavaReceiverInputDStream, JavaStreamingContext}
-import org.apache.spark.streaming.dstream.ReceiverInputDStream
+import org.apache.spark.streaming.api.java.{JavaReceiverInputDStream, JavaStreamingContext, JavaDStream}
+import org.apache.spark.streaming.dstream.{ReceiverInputDStream, DStream}
 
 object MQTTUtils {
   /**

external/twitter/src/main/scala/org/apache/spark/streaming/twitter/TwitterUtils.scala

@@ -21,8 +21,8 @@ import twitter4j.Status
 import twitter4j.auth.Authorization
 import org.apache.spark.storage.StorageLevel
 import org.apache.spark.streaming.StreamingContext
-import org.apache.spark.streaming.api.java.{JavaReceiverInputDStream, JavaStreamingContext}
-import org.apache.spark.streaming.dstream.ReceiverInputDStream
+import org.apache.spark.streaming.api.java.{JavaReceiverInputDStream, JavaDStream, JavaStreamingContext}
+import org.apache.spark.streaming.dstream.{ReceiverInputDStream, DStream}
 
 object TwitterUtils {
   /**