[SPARK-20156][CORE][SQL][STREAMING][MLLIB] Java String toLowerCase "Turkish locale bug" causes Spark problems

## What changes were proposed in this pull request?

Add Locale.ROOT to internal calls to String `toLowerCase`, `toUpperCase`, to avoid inadvertent locale-sensitive variation in behavior (aka the "Turkish locale problem").

The change looks large but it is just adding `Locale.ROOT` (the locale with no country or language specified) to every call to these methods.

## How was this patch tested?

Existing tests.

Author: Sean Owen <sowen@cloudera.com>

Closes #17527 from srowen/SPARK-20156.

1 files changed, 2 insertions, 1 deletions

diff --git a/repl/scala-2.11/src/main/scala/org/apache/spark/repl/Main.scala b/repl/scala-2.11/src/main/scala/org/apache/spark/repl/Main.scala
index 7f2ec01cc9..39fc621de7 100644
--- a/repl/scala-2.11/src/main/scala/org/apache/spark/repl/Main.scala
+++ b/repl/scala-2.11/src/main/scala/org/apache/spark/repl/Main.scala
@@ -18,6 +18,7 @@
 package org.apache.spark.repl
 
 import java.io.File
+import java.util.Locale
 
 import scala.tools.nsc.GenericRunnerSettings
 
@@ -88,7 +89,7 @@ object Main extends Logging {
     }
 
     val builder = SparkSession.builder.config(conf)
-    if (conf.get(CATALOG_IMPLEMENTATION.key, "hive").toLowerCase == "hive") {
+    if (conf.get(CATALOG_IMPLEMENTATION.key, "hive").toLowerCase(Locale.ROOT) == "hive") {
       if (SparkSession.hiveClassesArePresent) {
         // In the case that the property is not set at all, builder's config
         // does not have this value set to 'hive' yet. The original default