[MINOR][BUILD] Fix build warnings and Java lint errors

## What changes were proposed in this pull request?

Fix build warnings and Java lint errors. This just helps a bit in evaluating (new) warnings in another PR I have open.

## How was this patch tested?

Existing tests

Author: Sean Owen <sowen@cloudera.com>

Closes apache#19051 from srowen/JavaWarnings.

common/kvstore/src/main/java/org/apache/spark/util/kvstore/InMemoryStore.java

@@ -171,7 +171,7 @@ public int size() {
     public <T> InMemoryView<T> view(Class<T> type) {
       Preconditions.checkArgument(ti.type().equals(type), "Unexpected type: %s", type);
       Collection<T> all = (Collection<T>) data.values();
-      return new InMemoryView(type, all, ti);
+      return new InMemoryView<>(type, all, ti);
     }
 
   }

common/kvstore/src/main/java/org/apache/spark/util/kvstore/KVStoreIterator.java

@@ -17,6 +17,7 @@
 
 package org.apache.spark.util.kvstore;
 
+import java.io.Closeable;
 import java.util.Iterator;
 import java.util.List;
 
@@ -31,7 +32,7 @@
  * </p>
  */
 @Private
-public interface KVStoreIterator<T> extends Iterator<T>, AutoCloseable {
+public interface KVStoreIterator<T> extends Iterator<T>, Closeable {
 
   /**
    * Retrieve multiple elements from the store.

common/network-common/src/test/java/org/apache/spark/network/TransportRequestHandlerSuite.java

@@ -102,7 +102,7 @@ public void handleFetchRequestAndStreamRequest() throws Exception {
 
   private class ExtendedChannelPromise extends DefaultChannelPromise {
 
-    private List<GenericFutureListener> listeners = new ArrayList<>();
+    private List<GenericFutureListener<Future<Void>>> listeners = new ArrayList<>();
     private boolean success;
 
     ExtendedChannelPromise(Channel channel) {
@@ -113,7 +113,10 @@ private class ExtendedChannelPromise extends DefaultChannelPromise {
     @Override
     public ChannelPromise addListener(
         GenericFutureListener<? extends Future<? super Void>> listener) {
-      listeners.add(listener);
+      @SuppressWarnings("unchecked")
+      GenericFutureListener<Future<Void>> gfListener =
+          (GenericFutureListener<Future<Void>>) listener;
+      listeners.add(gfListener);
       return super.addListener(listener);
     }
 

core/src/test/java/org/apache/spark/launcher/SparkLauncherSuite.java

@@ -21,7 +21,6 @@
 import java.util.HashMap;
 import java.util.Map;
 
-import org.junit.Before;
 import org.junit.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

launcher/src/test/java/org/apache/spark/launcher/ChildProcAppHandleSuite.java

@@ -18,7 +18,6 @@
 package org.apache.spark.launcher;
 
 import java.io.File;
-import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;

mllib/src/test/scala/org/apache/spark/ml/tuning/CrossValidatorSuite.scala

@@ -187,14 +187,13 @@ class CrossValidatorSuite
     cv2.getEstimator match {
       case ova2: OneVsRest =>
         assert(ova.uid === ova2.uid)
-        val classifier = ova2.getClassifier
-        classifier match {
+        ova2.getClassifier match {
           case lr: LogisticRegression =>
             assert(ova.getClassifier.asInstanceOf[LogisticRegression].getMaxIter
               === lr.getMaxIter)
-          case _ =>
+          case other =>
             throw new AssertionError(s"Loaded CrossValidator expected estimator of type" +
-              s" LogisticREgression but found ${classifier.getClass.getName}")
+              s" LogisticRegression but found ${other.getClass.getName}")
         }
 
       case other =>

mllib/src/test/scala/org/apache/spark/ml/tuning/TrainValidationSplitSuite.scala

@@ -173,14 +173,13 @@ class TrainValidationSplitSuite
     tvs2.getEstimator match {
       case ova2: OneVsRest =>
         assert(ova.uid === ova2.uid)
-        val classifier = ova2.getClassifier
-        classifier match {
+        ova2.getClassifier match {
           case lr: LogisticRegression =>
             assert(ova.getClassifier.asInstanceOf[LogisticRegression].getMaxIter
               === lr.getMaxIter)
-          case _ =>
+          case other =>
             throw new AssertionError(s"Loaded TrainValidationSplit expected estimator of type" +
-              s" LogisticREgression but found ${classifier.getClass.getName}")
+              s" LogisticRegression but found ${other.getClass.getName}")
         }
 
       case other =>

pom.xml

@@ -2058,7 +2058,7 @@
               <javacArg>${java.version}</javacArg>
               <javacArg>-target</javacArg>
               <javacArg>${java.version}</javacArg>
-              <javacArg>-Xlint:all,-serial,-path</javacArg>
+              <javacArg>-Xlint:all,-serial,-path,-try</javacArg>
             </javacArgs>
           </configuration>
         </plugin>

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

@@ -350,7 +350,8 @@ private void decodeDictionaryIds(
    * is guaranteed that num is smaller than the number of values left in the current page.
    */
 
-  private void readBooleanBatch(int rowId, int num, WritableColumnVector column) throws IOException {
+  private void readBooleanBatch(int rowId, int num, WritableColumnVector column)
+      throws IOException {
     assert(column.dataType() == DataTypes.BooleanType);
     defColumn.readBooleans(
         num, column, rowId, maxDefLevel, (VectorizedValuesReader) dataColumn);

sql/core/src/main/java/org/apache/spark/sql/execution/vectorized/AggregateHashMap.java

@@ -21,7 +21,6 @@
 
 import com.google.common.annotations.VisibleForTesting;
 
-import org.apache.spark.memory.MemoryMode;
 import org.apache.spark.sql.types.StructType;
 
 import static org.apache.spark.sql.types.DataTypes.LongType;

sql/core/src/main/java/org/apache/spark/sql/execution/vectorized/ArrowColumnVector.java

@@ -21,7 +21,6 @@
 import org.apache.arrow.vector.complex.*;
 import org.apache.arrow.vector.holders.NullableVarCharHolder;
 
-import org.apache.spark.memory.MemoryMode;
 import org.apache.spark.sql.execution.arrow.ArrowUtils;
 import org.apache.spark.sql.types.*;
 import org.apache.spark.unsafe.types.UTF8String;