[CARBONDATA-3889] Cleanup code for carbondata-streaming module

Why is this PR needed?
need cleanup code in carbondata-streaming module

What changes were proposed in this PR?
Cleanup code in carbondata-streaming module

Does this PR introduce any user interface change?
No
Yes. (please explain the change and update document)

Is any new testcase added?
No
Yes

This closes #3826

streaming/pom.xml

@@ -1,3 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+    Licensed to the Apache Software Foundation (ASF) under one or more
+    contributor license agreements.  See the NOTICE file distributed with
+    this work for additional information regarding copyright ownership.
+    The ASF licenses this file to You under the Apache License, Version 2.0
+    (the "License"); you may not use this file except in compliance with
+    the License.  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+-->
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <parent>
     <artifactId>carbondata-parent</artifactId>
@@ -95,7 +112,7 @@
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
         <version>2.18</version>
-        <!-- Note config is repeated in scalatest config -->
+        <!-- Note config is repeated in scala test config -->
         <configuration>
           <reportsDirectory>${project.build.directory}/surefire-reports</reportsDirectory>
           <argLine>-Xmx3g -XX:MaxPermSize=512m -XX:ReservedCodeCacheSize=512m</argLine>

streaming/src/main/java/org/apache/carbondata/streaming/CarbonStreamRecordWriter.java

@@ -82,7 +82,7 @@ public class CarbonStreamRecordWriter extends RecordWriter<Void, Object> {
   private RowParser rowParser;
   private BadRecordsLogger badRecordLogger;
   private RowConverter converter;
-  private CarbonRow currentRow = new CarbonRow(null);
+  private final CarbonRow currentRow = new CarbonRow(null);
 
   // encoder
   private DataField[] dataFields;
@@ -174,7 +174,7 @@ private void initializeAtFirstRow() throws IOException {
     if (carbonFile.exists()) {
       // if the file is existed, use the append api
       outputStream = FileFactory.getDataOutputStreamUsingAppend(filePath);
-      // get the compressor from the fileheader. In legacy store,
+      // get the compressor from the file header. In legacy store,
       // the compressor name is not set and it use snappy compressor
       FileHeader header = new CarbonHeaderReader(filePath).readHeader();
       if (header.isSetCompressor_name()) {
@@ -329,7 +329,7 @@ private void appendBlockletToDataFile() throws IOException {
     if (output.getRowIndex() == -1) {
       return;
     }
-    output.apppendBlocklet(outputStream);
+    output.appendBlocklet(outputStream);
     outputStream.flush();
     if (!isClosed) {
       batchMinMaxIndex = StreamSegment.mergeBlockletMinMax(

streaming/src/main/java/org/apache/carbondata/streaming/StreamBlockletWriter.java

@@ -44,14 +44,14 @@ public class StreamBlockletWriter {
   private byte[] buffer;
   private int maxSize;
   private int maxRowNum;
-  private int rowSize;
+  private final int rowSize;
   private int count = 0;
   private int rowIndex = -1;
-  private Compressor compressor;
+  private final Compressor compressor;
 
-  private int dimCountWithoutComplex;
-  private int measureCount;
-  private DataType[] measureDataTypes;
+  private final int dimCountWithoutComplex;
+  private final int measureCount;
+  private final DataType[] measureDataTypes;
 
   // blocklet level stats
   ColumnPageStatsCollector[] dimStatsCollectors;
@@ -93,11 +93,11 @@ private void initializeStatsCollector() {
   }
 
   private void ensureCapacity(int space) {
-    int newcount = space + count;
-    if (newcount > buffer.length) {
-      byte[] newbuf = new byte[Math.max(newcount, buffer.length + rowSize)];
-      System.arraycopy(buffer, 0, newbuf, 0, count);
-      buffer = newbuf;
+    int newCount = space + count;
+    if (newCount > buffer.length) {
+      byte[] newBuffer = new byte[Math.max(newCount, buffer.length + rowSize)];
+      System.arraycopy(buffer, 0, newBuffer, 0, count);
+      buffer = newBuffer;
     }
   }
 
@@ -212,7 +212,7 @@ BlockletMinMaxIndex generateBlockletMinMax() {
     return blockletMinMaxIndex;
   }
 
-  void apppendBlocklet(DataOutputStream outputStream) throws IOException {
+  void appendBlocklet(DataOutputStream outputStream) throws IOException {
     outputStream.write(CarbonStreamOutputFormat.CARBON_SYNC_MARKER);
 
     BlockletInfo blockletInfo = new BlockletInfo();