[SPARK-14444][BUILD] Add a new scalastyle `NoScalaDoc` to prevent ScalaDoc-style multiline comments

## What changes were proposed in this pull request?

According to the [Spark Code Style Guide](https://cwiki.apache.org/confluence/display/SPARK/Spark+Code+Style+Guide#SparkCodeStyleGuide-Indentation), this PR adds a new scalastyle rule to prevent the followings.
```
/** In Spark, we don't use the ScalaDoc style so this
  * is not correct.
  */
```

## How was this patch tested?

Pass the Jenkins tests (including `lint-scala`).

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #12221 from dongjoon-hyun/SPARK-14444.

3 files changed, 12 insertions, 10 deletions

diff --git a/core/src/main/scala/org/apache/spark/SparkConf.scala b/core/src/main/scala/org/apache/spark/SparkConf.scala
index 5da2e98f1f..e0fd248c43 100644
--- a/core/src/main/scala/org/apache/spark/SparkConf.scala
+++ b/core/src/main/scala/org/apache/spark/SparkConf.scala
@@ -419,8 +419,10 @@ class SparkConf(loadDefaults: Boolean) extends Cloneable with Logging {
    */
   private[spark] def getenv(name: String): String = System.getenv(name)
 
-  /** Checks for illegal or deprecated config settings. Throws an exception for the former. Not
-    * idempotent - may mutate this conf object to convert deprecated settings to supported ones. */
+  /**
+   * Checks for illegal or deprecated config settings. Throws an exception for the former. Not
+   * idempotent - may mutate this conf object to convert deprecated settings to supported ones.
+   */
   private[spark] def validateSettings() {
     if (contains("spark.local.dir")) {
       val msg = "In Spark 1.0 and later spark.local.dir will be overridden by the value set by " +
diff --git a/core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala b/core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala
index 4e8e363635..41ac308808 100644
--- a/core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala
@@ -76,9 +76,9 @@ class SparkHadoopUtil extends Logging {
 
 
   /**
-    * Appends S3-specific, spark.hadoop.*, and spark.buffer.size configurations to a Hadoop
-    * configuration.
-    */
+   * Appends S3-specific, spark.hadoop.*, and spark.buffer.size configurations to a Hadoop
+   * configuration.
+   */
   def appendS3AndSparkHadoopConfigurations(conf: SparkConf, hadoopConf: Configuration): Unit = {
     // Note: this null check is around more than just access to the "conf" object to maintain
     // the behavior of the old implementation of this code, for backwards compatibility.
@@ -108,9 +108,9 @@ class SparkHadoopUtil extends Logging {
   }
 
   /**
-    * Return an appropriate (subclass) of Configuration. Creating config can initializes some Hadoop
-    * subsystems.
-    */
+   * Return an appropriate (subclass) of Configuration. Creating config can initializes some Hadoop
+   * subsystems.
+   */
   def newConfiguration(conf: SparkConf): Configuration = {
     val hadoopConf = new Configuration()
     appendS3AndSparkHadoopConfigurations(conf, hadoopConf)
diff --git a/core/src/main/scala/org/apache/spark/partial/BoundedDouble.scala b/core/src/main/scala/org/apache/spark/partial/BoundedDouble.scala
index d06b2c67d2..c562c70aba 100644
--- a/core/src/main/scala/org/apache/spark/partial/BoundedDouble.scala
+++ b/core/src/main/scala/org/apache/spark/partial/BoundedDouble.scala
@@ -28,8 +28,8 @@ class BoundedDouble(val mean: Double, val confidence: Double, val low: Double, v
     this.mean.hashCode ^ this.confidence.hashCode ^ this.low.hashCode ^ this.high.hashCode
 
   /**
-    * Note that consistent with Double, any NaN value will make equality false
-    */
+   * Note that consistent with Double, any NaN value will make equality false
+   */
   override def equals(that: Any): Boolean =
     that match {
       case that: BoundedDouble => {