[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, 4 insertions, 2 deletions

diff --git a/sql/catalyst/src/test/java/org/apache/spark/sql/streaming/JavaOutputModeSuite.java b/sql/catalyst/src/test/java/org/apache/spark/sql/streaming/JavaOutputModeSuite.java
index e0a54fe30a..d8845e0c83 100644
--- a/sql/catalyst/src/test/java/org/apache/spark/sql/streaming/JavaOutputModeSuite.java
+++ b/sql/catalyst/src/test/java/org/apache/spark/sql/streaming/JavaOutputModeSuite.java
@@ -17,6 +17,8 @@
 
 package org.apache.spark.sql.streaming;
 
+import java.util.Locale;
+
 import org.junit.Test;
 
 public class JavaOutputModeSuite {
@@ -24,8 +26,8 @@ public class JavaOutputModeSuite {
   @Test
   public void testOutputModes() {
     OutputMode o1 = OutputMode.Append();
-    assert(o1.toString().toLowerCase().contains("append"));
+    assert(o1.toString().toLowerCase(Locale.ROOT).contains("append"));
     OutputMode o2 = OutputMode.Complete();
-    assert (o2.toString().toLowerCase().contains("complete"));
+    assert (o2.toString().toLowerCase(Locale.ROOT).contains("complete"));
   }
 }