[SPARK-3854][BUILD] Scala style: require spaces before `{`.

## What changes were proposed in this pull request?

Since the opening curly brace, '{', has many usages as discussed in [SPARK-3854](https://issues.apache.org/jira/browse/SPARK-3854), this PR adds a ScalaStyle rule to prevent '){' pattern  for the following majority pattern and fixes the code accordingly. If we enforce this in ScalaStyle from now, it will improve the Scala code quality and reduce review time.
```
// Correct:
if (true) {
  println("Wow!")
}

// Incorrect:
if (true){
   println("Wow!")
}
```
IntelliJ also shows new warnings based on this.

## How was this patch tested?

Pass the Jenkins ScalaStyle test.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #11637 from dongjoon-hyun/SPARK-3854.

6 files changed, 8 insertions, 8 deletions

diff --git a/examples/src/main/scala/org/apache/spark/examples/LocalFileLR.scala b/examples/src/main/scala/org/apache/spark/examples/LocalFileLR.scala
index f2e4c96fa5..bec89f7c3d 100644
--- a/examples/src/main/scala/org/apache/spark/examples/LocalFileLR.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/LocalFileLR.scala
@@ -58,7 +58,7 @@ object LocalFileLR {
     val ITERATIONS = args(1).toInt
 
     // Initialize w to a random value
-    var w = DenseVector.fill(D){2 * rand.nextDouble - 1}
+    var w = DenseVector.fill(D) {2 * rand.nextDouble - 1}
     println("Initial w: " + w)
 
     for (i <- 1 to ITERATIONS) {
diff --git a/examples/src/main/scala/org/apache/spark/examples/LocalKMeans.scala b/examples/src/main/scala/org/apache/spark/examples/LocalKMeans.scala
index 19bebffcb0..f8961847f3 100644
--- a/examples/src/main/scala/org/apache/spark/examples/LocalKMeans.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/LocalKMeans.scala
@@ -41,7 +41,7 @@ object LocalKMeans {
 
   def generateData: Array[DenseVector[Double]] = {
     def generatePoint(i: Int): DenseVector[Double] = {
-      DenseVector.fill(D){rand.nextDouble * R}
+      DenseVector.fill(D) {rand.nextDouble * R}
     }
     Array.tabulate(N)(generatePoint)
   }
diff --git a/examples/src/main/scala/org/apache/spark/examples/LocalLR.scala b/examples/src/main/scala/org/apache/spark/examples/LocalLR.scala
index 58adbabe44..0baf6db607 100644
--- a/examples/src/main/scala/org/apache/spark/examples/LocalLR.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/LocalLR.scala
@@ -41,7 +41,7 @@ object LocalLR {
   def generateData: Array[DataPoint] = {
     def generatePoint(i: Int): DataPoint = {
       val y = if (i % 2 == 0) -1 else 1
-      val x = DenseVector.fill(D){rand.nextGaussian + y * R}
+      val x = DenseVector.fill(D) {rand.nextGaussian + y * R}
       DataPoint(x, y)
     }
     Array.tabulate(N)(generatePoint)
@@ -62,7 +62,7 @@ object LocalLR {
 
     val data = generateData
     // Initialize w to a random value
-    var w = DenseVector.fill(D){2 * rand.nextDouble - 1}
+    var w = DenseVector.fill(D) {2 * rand.nextDouble - 1}
     println("Initial w: " + w)
 
     for (i <- 1 to ITERATIONS) {
diff --git a/examples/src/main/scala/org/apache/spark/examples/SparkHdfsLR.scala b/examples/src/main/scala/org/apache/spark/examples/SparkHdfsLR.scala
index f7eb9e9936..7463b868ff 100644
--- a/examples/src/main/scala/org/apache/spark/examples/SparkHdfsLR.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/SparkHdfsLR.scala
@@ -78,7 +78,7 @@ object SparkHdfsLR {
     val ITERATIONS = args(1).toInt
 
     // Initialize w to a random value
-    var w = DenseVector.fill(D){2 * rand.nextDouble - 1}
+    var w = DenseVector.fill(D) {2 * rand.nextDouble - 1}
     println("Initial w: " + w)
 
     for (i <- 1 to ITERATIONS) {
diff --git a/examples/src/main/scala/org/apache/spark/examples/SparkLR.scala b/examples/src/main/scala/org/apache/spark/examples/SparkLR.scala
index 036e3d24c9..acd8656b65 100644
--- a/examples/src/main/scala/org/apache/spark/examples/SparkLR.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/SparkLR.scala
@@ -46,7 +46,7 @@ object SparkLR {
   def generateData: Array[DataPoint] = {
     def generatePoint(i: Int): DataPoint = {
       val y = if (i % 2 == 0) -1 else 1
-      val x = DenseVector.fill(D){rand.nextGaussian + y * R}
+      val x = DenseVector.fill(D) {rand.nextGaussian + y * R}
       DataPoint(x, y)
     }
     Array.tabulate(N)(generatePoint)
@@ -71,7 +71,7 @@ object SparkLR {
     val points = sc.parallelize(generateData, numSlices).cache()
 
     // Initialize w to a random value
-    var w = DenseVector.fill(D){2 * rand.nextDouble - 1}
+    var w = DenseVector.fill(D) {2 * rand.nextDouble - 1}
     println("Initial w: " + w)
 
     for (i <- 1 to ITERATIONS) {
diff --git a/examples/src/main/scala/org/apache/spark/examples/streaming/ActorWordCount.scala b/examples/src/main/scala/org/apache/spark/examples/streaming/ActorWordCount.scala
index 2770b8af1c..844772a289 100644
--- a/examples/src/main/scala/org/apache/spark/examples/streaming/ActorWordCount.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/streaming/ActorWordCount.scala
@@ -100,7 +100,7 @@ class SampleActorReceiver[T](urlOfPublisher: String) extends ActorReceiver {
 object FeederActor {
 
   def main(args: Array[String]) {
-    if (args.length < 2){
+    if (args.length < 2) {
       System.err.println("Usage: FeederActor <hostname> <port>\n")
       System.exit(1)
     }