[MINOR][BUILD] Fix Java linter errors

This PR cleans up a few Java linter errors for Apache Spark 2.2 release.

```bash
$ dev/lint-java
Using `mvn` from path: /usr/local/bin/mvn
Checkstyle checks passed.
```

We can check the result at Travis CI, [here](https://travis-ci.org/dongjoon-hyun/spark/builds/244297894).

Author: Dongjoon Hyun <[email protected]>

Closes apache#18345 from dongjoon-hyun/fix_lint_java_2.

(cherry picked from commit ecc5631)
Signed-off-by: Sean Owen <[email protected]>

Author: dongjoon-hyun

common/network-shuffle/src/main/java/org/apache/spark/network/shuffle/OneForOneBlockFetcher.java

@@ -157,7 +157,7 @@ private class DownloadCallback implements StreamCallback {
     private File targetFile = null;
     private int chunkIndex;
 
-    public DownloadCallback(File targetFile, int chunkIndex) throws IOException {
+    DownloadCallback(File targetFile, int chunkIndex) throws IOException {
       this.targetFile = targetFile;
       this.channel = Channels.newChannel(new FileOutputStream(targetFile));
       this.chunkIndex = chunkIndex;

core/src/main/java/org/apache/spark/shuffle/sort/UnsafeShuffleWriter.java

@@ -353,8 +353,9 @@ private long[] mergeSpillsWithFileStream(
       }
       for (int partition = 0; partition < numPartitions; partition++) {
         final long initialFileLength = mergedFileOutputStream.getByteCount();
-        // Shield the underlying output stream from close() calls, so that we can close the higher
-        // level streams to make sure all data is really flushed and internal state is cleaned.
+        // Shield the underlying output stream from close() calls, so that we can close
+        // the higher level streams to make sure all data is really flushed and internal state is
+        // cleaned.
         OutputStream partitionOutput = new CloseShieldOutputStream(
           new TimeTrackingOutputStream(writeMetrics, mergedFileOutputStream));
         partitionOutput = blockManager.serializerManager().wrapForEncryption(partitionOutput);

examples/src/main/java/org/apache/spark/examples/ml/JavaALSExample.java

@@ -121,7 +121,7 @@ public static void main(String[] args) {
     // $example off$
     userRecs.show();
     movieRecs.show();
-    
+
     spark.stop();
   }
 }

examples/src/main/java/org/apache/spark/examples/sql/JavaSQLDataSourceExample.java

@@ -124,7 +124,11 @@ private static void runBasicDataSourceExample(SparkSession spark) {
     peopleDF.write().bucketBy(42, "name").sortBy("age").saveAsTable("people_bucketed");
     // $example off:write_sorting_and_bucketing$
     // $example on:write_partitioning$
-    usersDF.write().partitionBy("favorite_color").format("parquet").save("namesPartByColor.parquet");
+    usersDF
+      .write()
+      .partitionBy("favorite_color")
+      .format("parquet")
+      .save("namesPartByColor.parquet");
     // $example off:write_partitioning$
     // $example on:write_partition_and_bucket$
     peopleDF

sql/catalyst/src/main/java/org/apache/spark/sql/streaming/OutputMode.java

@@ -17,7 +17,6 @@
 
 package org.apache.spark.sql.streaming;
 
-import org.apache.spark.annotation.Experimental;
 import org.apache.spark.annotation.InterfaceStability;
 import org.apache.spark.sql.catalyst.streaming.InternalOutputModes;