[MINOR][BUILD] Fix lint-java breaks.

## What changes were proposed in this pull request?

This PR proposes to fix the lint-breaks as below:
```
[ERROR] src/main/java/org/apache/spark/unsafe/Platform.java:[51] (regexp) RegexpSingleline: No trailing whitespace allowed.
[ERROR] src/main/scala/org/apache/spark/sql/streaming/Trigger.java:[45,25] (naming) MethodName: Method name 'ProcessingTime' must match pattern '^[a-z][a-z0-9][a-zA-Z0-9_]*$'.
[ERROR] src/main/scala/org/apache/spark/sql/streaming/Trigger.java:[62,25] (naming) MethodName: Method name 'ProcessingTime' must match pattern '^[a-z][a-z0-9][a-zA-Z0-9_]*$'.
[ERROR] src/main/scala/org/apache/spark/sql/streaming/Trigger.java:[78,25] (naming) MethodName: Method name 'ProcessingTime' must match pattern '^[a-z][a-z0-9][a-zA-Z0-9_]*$'.
[ERROR] src/main/scala/org/apache/spark/sql/streaming/Trigger.java:[92,25] (naming) MethodName: Method name 'ProcessingTime' must match pattern '^[a-z][a-z0-9][a-zA-Z0-9_]*$'.
[ERROR] src/main/scala/org/apache/spark/sql/streaming/Trigger.java:[102,25] (naming) MethodName: Method name 'Once' must match pattern '^[a-z][a-z0-9][a-zA-Z0-9_]*$'.
[ERROR] src/test/java/org/apache/spark/streaming/kinesis/JavaKinesisInputDStreamBuilderSuite.java:[28,8] (imports) UnusedImports: Unused import - org.apache.spark.streaming.api.java.JavaDStream.
```

after:
```
dev/lint-java
Checkstyle checks passed.
```
[Test Result](https://travis-ci.org/ConeyLiu/spark/jobs/229666169)

## How was this patch tested?

Travis CI

Author: Xianyang Liu <[email protected]>

Closes #17890 from ConeyLiu/codestyle.

Author: ConeyLiu

common/unsafe/src/main/java/org/apache/spark/unsafe/Platform.java

@@ -48,7 +48,7 @@ public final class Platform {
     boolean _unaligned;
     String arch = System.getProperty("os.arch", "");
     if (arch.equals("ppc64le") || arch.equals("ppc64")) {
-      // Since java.nio.Bits.unaligned() doesn't return true on ppc (See JDK-8165231), but 
+      // Since java.nio.Bits.unaligned() doesn't return true on ppc (See JDK-8165231), but
       // ppc64 and ppc64le support it
       _unaligned = true;
     } else {

core/src/main/scala/org/apache/spark/storage/BlockManager.scala

@@ -29,8 +29,6 @@ import scala.reflect.ClassTag
 import scala.util.Random
 import scala.util.control.NonFatal
 
-import com.google.common.io.ByteStreams
-
 import org.apache.spark._
 import org.apache.spark.executor.{DataReadMethod, ShuffleWriteMetrics}
 import org.apache.spark.internal.Logging
@@ -41,7 +39,6 @@ import org.apache.spark.network.netty.SparkTransportConf
 import org.apache.spark.network.shuffle.ExternalShuffleClient
 import org.apache.spark.network.shuffle.protocol.ExecutorShuffleInfo
 import org.apache.spark.rpc.RpcEnv
-import org.apache.spark.security.CryptoStreamUtils
 import org.apache.spark.serializer.{SerializerInstance, SerializerManager}
 import org.apache.spark.shuffle.ShuffleManager
 import org.apache.spark.storage.memory._

dev/checkstyle-suppressions.xml

@@ -47,5 +47,5 @@
     <suppress checks="MethodName"
               files="sql/catalyst/src/main/java/org/apache/spark/sql/streaming/GroupStateTimeout.java"/>
     <suppress checks="MethodName"
-              files="sql/catalyst/src/main/java/org/apache/spark/sql/streaming/Trigger.java"/>
+              files="sql/core/src/main/java/org/apache/spark/sql/streaming/Trigger.java"/>
 </suppressions>

external/kinesis-asl/src/test/java/org/apache/spark/streaming/kinesis/JavaKinesisInputDStreamBuilderSuite.java

@@ -25,7 +25,6 @@
 import org.apache.spark.streaming.Duration;
 import org.apache.spark.streaming.Seconds;
 import org.apache.spark.streaming.LocalJavaStreamingContext;
-import org.apache.spark.streaming.api.java.JavaDStream;
 
 public class JavaKinesisInputDStreamBuilderSuite extends LocalJavaStreamingContext {
   /**