[SPARK-14868][BUILD] Enable NewLineAtEofChecker in checkstyle and fix lint-java errors

## What changes were proposed in this pull request?

Spark uses `NewLineAtEofChecker` rule in Scala by ScalaStyle. And, most Java code also comply with the rule. This PR aims to enforce the same rule `NewlineAtEndOfFile` by CheckStyle explicitly. Also, this fixes lint-java errors since SPARK-14465. The followings are the items.

- Adds a new line at the end of the files (19 files)
- Fixes 25 lint-java errors (12 RedundantModifier, 6 **ArrayTypeStyle**, 2 LineLength, 2 UnusedImports, 2 RegexpSingleline, 1 ModifierOrder)

## How was this patch tested?

After the Jenkins test succeeds, `dev/lint-java` should pass. (Currently, Jenkins dose not run lint-java.)
```bash
$ dev/lint-java
Using `mvn` from path: /usr/local/bin/mvn
Checkstyle checks passed.
```

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #12632 from dongjoon-hyun/SPARK-14868.

mllib/src/main/scala/org/apache/spark/mllib/package-info.java

@@ -18,4 +18,4 @@
 /**
  * Spark's machine learning library.
  */
-package org.apache.spark.mllib;
+package org.apache.spark.mllib;
\ No newline at end of file

mllib/src/test/java/org/apache/spark/ml/classification/JavaRandomForestClassifierSuite.java

@@ -81,15 +81,15 @@ public class JavaRandomForestClassifierSuite implements Serializable {
     for (String featureSubsetStrategy: RandomForestClassifier.supportedFeatureSubsetStrategies()) {
       rf.setFeatureSubsetStrategy(featureSubsetStrategy);
     }
-    String realStrategies[] = {".1", ".10", "0.10", "0.1", "0.9", "1.0"};
+    String[] realStrategies = {".1", ".10", "0.10", "0.1", "0.9", "1.0"};
     for (String strategy: realStrategies) {
       rf.setFeatureSubsetStrategy(strategy);
     }
-    String integerStrategies[] = {"1", "10", "100", "1000", "10000"};
+    String[] integerStrategies = {"1", "10", "100", "1000", "10000"};
     for (String strategy: integerStrategies) {
       rf.setFeatureSubsetStrategy(strategy);
     }
-    String invalidStrategies[] = {"-.1", "-.10", "-0.10", ".0", "0.0", "1.1", "0"};
+    String[] invalidStrategies = {"-.1", "-.10", "-0.10", ".0", "0.0", "1.1", "0"};
     for (String strategy: invalidStrategies) {
       try {
         rf.setFeatureSubsetStrategy(strategy);

mllib/src/test/java/org/apache/spark/ml/regression/JavaRandomForestRegressorSuite.java

@@ -81,15 +81,15 @@ public class JavaRandomForestRegressorSuite implements Serializable {
     for (String featureSubsetStrategy: RandomForestRegressor.supportedFeatureSubsetStrategies()) {
       rf.setFeatureSubsetStrategy(featureSubsetStrategy);
     }
-    String realStrategies[] = {".1", ".10", "0.10", "0.1", "0.9", "1.0"};
+    String[] realStrategies = {".1", ".10", "0.10", "0.1", "0.9", "1.0"};
     for (String strategy: realStrategies) {
       rf.setFeatureSubsetStrategy(strategy);
     }
-    String integerStrategies[] = {"1", "10", "100", "1000", "10000"};
+    String[] integerStrategies = {"1", "10", "100", "1000", "10000"};
     for (String strategy: integerStrategies) {
       rf.setFeatureSubsetStrategy(strategy);
     }
-    String invalidStrategies[] = {"-.1", "-.10", "-0.10", ".0", "0.0", "1.1", "0"};
+    String[] invalidStrategies = {"-.1", "-.10", "-0.10", ".0", "0.0", "1.1", "0"};
     for (String strategy: invalidStrategies) {
       try {
         rf.setFeatureSubsetStrategy(strategy);

sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/SpecificParquetRecordReaderBase.java

@@ -38,7 +38,6 @@ import static org.apache.parquet.hadoop.ParquetFileReader.readFooter;
 import static org.apache.parquet.hadoop.ParquetInputFormat.getFilter;
 
 import org.apache.hadoop.conf.Configuration;
-import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.mapreduce.InputSplit;
 import org.apache.hadoop.mapreduce.RecordReader;

streaming/src/main/scala/org/apache/spark/streaming/api/java/package-info.java

@@ -18,4 +18,4 @@
 /**
  * Java APIs for spark streaming.
  */
-package org.apache.spark.streaming.api.java;
+package org.apache.spark.streaming.api.java;
\ No newline at end of file

streaming/src/main/scala/org/apache/spark/streaming/dstream/package-info.java

@@ -18,4 +18,4 @@
 /**
  * Various implementations of DStreams.
  */
-package org.apache.spark.streaming.dstream;
+package org.apache.spark.streaming.dstream;
\ No newline at end of file