[SPARK-15618][SQL][MLLIB] Use SparkSession.builder.sparkContext if applicable.

## What changes were proposed in this pull request?

This PR changes function `SparkSession.builder.sparkContext(..)` from **private[sql]** into **private[spark]**, and uses it if applicable like the followings.
```
- val spark = SparkSession.builder().config(sc.getConf).getOrCreate()
+ val spark = SparkSession.builder().sparkContext(sc).getOrCreate()
```

## How was this patch tested?

Pass the existing Jenkins tests.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #13365 from dongjoon-hyun/SPARK-15618.

3 files changed, 4 insertions, 9 deletions

diff --git a/examples/src/main/scala/org/apache/spark/examples/BroadcastTest.scala b/examples/src/main/scala/org/apache/spark/examples/BroadcastTest.scala
index c50f25d951..a68fd0285f 100644
--- a/examples/src/main/scala/org/apache/spark/examples/BroadcastTest.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/BroadcastTest.scala
@@ -29,13 +29,10 @@ object BroadcastTest {
 
     val blockSize = if (args.length > 2) args(2) else "4096"
 
-    val sparkConf = new SparkConf()
-      .set("spark.broadcast.blockSize", blockSize)
-
     val spark = SparkSession
-      .builder
-      .config(sparkConf)
+      .builder()
       .appName("Broadcast Test")
+      .config("spark.broadcast.blockSize", blockSize)
       .getOrCreate()
 
     val sc = spark.sparkContext
diff --git a/examples/src/main/scala/org/apache/spark/examples/mllib/LDAExample.scala b/examples/src/main/scala/org/apache/spark/examples/mllib/LDAExample.scala
index 7651aade49..3fbf8e0333 100644
--- a/examples/src/main/scala/org/apache/spark/examples/mllib/LDAExample.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/mllib/LDAExample.scala
@@ -191,6 +191,7 @@ object LDAExample {
 
     val spark = SparkSession
       .builder
+      .sparkContext(sc)
       .getOrCreate()
     import spark.implicits._
 
diff --git a/examples/src/main/scala/org/apache/spark/examples/sql/hive/HiveFromSpark.scala b/examples/src/main/scala/org/apache/spark/examples/sql/hive/HiveFromSpark.scala
index d3bb7e4398..2d7a01a95d 100644
--- a/examples/src/main/scala/org/apache/spark/examples/sql/hive/HiveFromSpark.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/sql/hive/HiveFromSpark.scala
@@ -22,7 +22,6 @@ import java.io.File
 
 import com.google.common.io.{ByteStreams, Files}
 
-import org.apache.spark.SparkConf
 import org.apache.spark.sql._
 
 object HiveFromSpark {
@@ -35,8 +34,6 @@ object HiveFromSpark {
   ByteStreams.copy(kv1Stream, Files.newOutputStreamSupplier(kv1File))
 
   def main(args: Array[String]) {
-    val sparkConf = new SparkConf().setAppName("HiveFromSpark")
-
     // When working with Hive, one must instantiate `SparkSession` with Hive support, including
     // connectivity to a persistent Hive metastore, support for Hive serdes, and Hive user-defined
     // functions. Users who do not have an existing Hive deployment can still enable Hive support.
@@ -45,7 +42,7 @@ object HiveFromSpark {
     // which defaults to the directory `spark-warehouse` in the current directory that the spark
     // application is started.
     val spark = SparkSession.builder
-      .config(sparkConf)
+      .appName("HiveFromSpark")
       .enableHiveSupport()
       .getOrCreate()
     val sc = spark.sparkContext