[MINOR][SQL] Remove extra anonymous closure within functional transformations

## What changes were proposed in this pull request?

This PR removes extra anonymous closure within functional transformations.

For example,

```scala
.map(item => {
  ...
})
```

which can be just simply as below:

```scala
.map { item =>
  ...
}
```

## How was this patch tested?

Related unit tests and `sbt scalastyle`.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #12382 from HyukjinKwon/minor-extra-closers.

9 files changed, 18 insertions, 18 deletions

diff --git a/core/src/main/scala/org/apache/spark/SparkContext.scala b/core/src/main/scala/org/apache/spark/SparkContext.scala
index 966198dd5e..e41088f7c8 100644
--- a/core/src/main/scala/org/apache/spark/SparkContext.scala
+++ b/core/src/main/scala/org/apache/spark/SparkContext.scala
@@ -723,7 +723,7 @@ class SparkContext(config: SparkConf) extends Logging with ExecutorAllocationCli
         (safeEnd - safeStart) / step + 1
       }
     }
-    parallelize(0 until numSlices, numSlices).mapPartitionsWithIndex((i, _) => {
+    parallelize(0 until numSlices, numSlices).mapPartitionsWithIndex { (i, _) =>
       val partitionStart = (i * numElements) / numSlices * step + start
       val partitionEnd = (((i + 1) * numElements) / numSlices) * step + start
       def getSafeMargin(bi: BigInt): Long =
@@ -762,7 +762,7 @@ class SparkContext(config: SparkConf) extends Logging with ExecutorAllocationCli
           ret
         }
       }
-    })
+    }
   }
 
   /** Distribute a local Scala collection to form an RDD.
diff --git a/core/src/main/scala/org/apache/spark/deploy/master/Master.scala b/core/src/main/scala/org/apache/spark/deploy/master/Master.scala
index 9bd3fc1033..b443e8f051 100644
--- a/core/src/main/scala/org/apache/spark/deploy/master/Master.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/master/Master.scala
@@ -843,10 +843,10 @@ private[deploy] class Master(
       addressToApp -= app.driver.address
       if (completedApps.size >= RETAINED_APPLICATIONS) {
         val toRemove = math.max(RETAINED_APPLICATIONS / 10, 1)
-        completedApps.take(toRemove).foreach( a => {
+        completedApps.take(toRemove).foreach { a =>
           Option(appIdToUI.remove(a.id)).foreach { ui => webUi.detachSparkUI(ui) }
           applicationMetricsSystem.removeSource(a.appSource)
-        })
+        }
         completedApps.trimStart(toRemove)
       }
       completedApps += app // Remember it in our history
diff --git a/core/src/main/scala/org/apache/spark/rdd/BlockRDD.scala b/core/src/main/scala/org/apache/spark/rdd/BlockRDD.scala
index 8358244987..63d1d1767a 100644
--- a/core/src/main/scala/org/apache/spark/rdd/BlockRDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/BlockRDD.scala
@@ -35,9 +35,9 @@ class BlockRDD[T: ClassTag](sc: SparkContext, @transient val blockIds: Array[Blo
 
   override def getPartitions: Array[Partition] = {
     assertValid()
-    (0 until blockIds.length).map(i => {
+    (0 until blockIds.length).map { i =>
       new BlockRDDPartition(blockIds(i), i).asInstanceOf[Partition]
-    }).toArray
+    }.toArray
   }
 
   override def compute(split: Partition, context: TaskContext): Iterator[T] = {
diff --git a/core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala b/core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala
index ac5ba9e79f..f7c646c668 100644
--- a/core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala
@@ -422,7 +422,7 @@ private[spark] object HadoopRDD extends Logging {
 
   private[spark] def convertSplitLocationInfo(infos: Array[AnyRef]): Seq[String] = {
     val out = ListBuffer[String]()
-    infos.foreach { loc => {
+    infos.foreach { loc =>
       val locationStr = HadoopRDD.SPLIT_INFO_REFLECTIONS.get.
         getLocation.invoke(loc).asInstanceOf[String]
       if (locationStr != "localhost") {
@@ -434,7 +434,7 @@ private[spark] object HadoopRDD extends Logging {
           out += new HostTaskLocation(locationStr).toString
         }
       }
-    }}
+    }
     out.seq
   }
 }
diff --git a/core/src/main/scala/org/apache/spark/rdd/ParallelCollectionRDD.scala b/core/src/main/scala/org/apache/spark/rdd/ParallelCollectionRDD.scala
index 462fb39ea2..bb84e4af15 100644
--- a/core/src/main/scala/org/apache/spark/rdd/ParallelCollectionRDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/ParallelCollectionRDD.scala
@@ -121,11 +121,11 @@ private object ParallelCollectionRDD {
     // Sequences need to be sliced at the same set of index positions for operations
     // like RDD.zip() to behave as expected
     def positions(length: Long, numSlices: Int): Iterator[(Int, Int)] = {
-      (0 until numSlices).iterator.map(i => {
+      (0 until numSlices).iterator.map { i =>
         val start = ((i * length) / numSlices).toInt
         val end = (((i + 1) * length) / numSlices).toInt
         (start, end)
-      })
+      }
     }
     seq match {
       case r: Range =>
diff --git a/core/src/main/scala/org/apache/spark/rdd/PartitionerAwareUnionRDD.scala b/core/src/main/scala/org/apache/spark/rdd/PartitionerAwareUnionRDD.scala
index c3579d761d..0abba15bec 100644
--- a/core/src/main/scala/org/apache/spark/rdd/PartitionerAwareUnionRDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/PartitionerAwareUnionRDD.scala
@@ -68,9 +68,9 @@ class PartitionerAwareUnionRDD[T: ClassTag](
 
   override def getPartitions: Array[Partition] = {
     val numPartitions = partitioner.get.numPartitions
-    (0 until numPartitions).map(index => {
+    (0 until numPartitions).map { index =>
       new PartitionerAwareUnionRDDPartition(rdds, index)
-    }).toArray
+    }.toArray
   }
 
   // Get the location where most of the partitions of parent RDDs are located
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerUtils.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerUtils.scala
index 7295d50682..1e322ac679 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerUtils.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerUtils.scala
@@ -226,7 +226,7 @@ private[mesos] trait MesosSchedulerUtils extends Logging {
    * @return
    */
   protected def toAttributeMap(offerAttributes: JList[Attribute]): Map[String, GeneratedMessage] = {
-    offerAttributes.asScala.map(attr => {
+    offerAttributes.asScala.map { attr =>
       val attrValue = attr.getType match {
         case Value.Type.SCALAR => attr.getScalar
         case Value.Type.RANGES => attr.getRanges
@@ -234,7 +234,7 @@ private[mesos] trait MesosSchedulerUtils extends Logging {
         case Value.Type.TEXT => attr.getText
       }
       (attr.getName, attrValue)
-    }).toMap
+    }.toMap
   }
 
 
diff --git a/core/src/main/scala/org/apache/spark/shuffle/BlockStoreShuffleReader.scala b/core/src/main/scala/org/apache/spark/shuffle/BlockStoreShuffleReader.scala
index 637b2dfc19..876cdfaa87 100644
--- a/core/src/main/scala/org/apache/spark/shuffle/BlockStoreShuffleReader.scala
+++ b/core/src/main/scala/org/apache/spark/shuffle/BlockStoreShuffleReader.scala
@@ -69,10 +69,10 @@ private[spark] class BlockStoreShuffleReader[K, C](
     // Update the context task metrics for each record read.
     val readMetrics = context.taskMetrics.registerTempShuffleReadMetrics()
     val metricIter = CompletionIterator[(Any, Any), Iterator[(Any, Any)]](
-      recordIter.map(record => {
+      recordIter.map { record =>
         readMetrics.incRecordsRead(1)
         record
-      }),
+      },
       context.taskMetrics().mergeShuffleReadMetrics())
 
     // An interruptible iterator must be used here in order to support task cancellation
diff --git a/core/src/main/scala/org/apache/spark/ui/jobs/ExecutorTable.scala b/core/src/main/scala/org/apache/spark/ui/jobs/ExecutorTable.scala
index 1304efd8f2..f609fb4cd2 100644
--- a/core/src/main/scala/org/apache/spark/ui/jobs/ExecutorTable.scala
+++ b/core/src/main/scala/org/apache/spark/ui/jobs/ExecutorTable.scala
@@ -42,13 +42,13 @@ private[ui] class ExecutorTable(stageId: Int, stageAttemptId: Int, parent: Stage
     var hasShuffleWrite = false
     var hasShuffleRead = false
     var hasBytesSpilled = false
-    stageData.foreach(data => {
+    stageData.foreach { data =>
         hasInput = data.hasInput
         hasOutput = data.hasOutput
         hasShuffleRead = data.hasShuffleRead
         hasShuffleWrite = data.hasShuffleWrite
         hasBytesSpilled = data.hasBytesSpilled
-    })
+    }
 
     <table class={UIUtils.TABLE_CLASS_STRIPED_SORTABLE}>
       <thead>