BAEL-1226 Checkstyle introduction. (#3736)

* BAEL-1226:- Changes for checkstyle

* BAEL-1226: Changes for checkstyle

* Changes for BAEL-1226:- Chnaged the file to match in article.

* Formatting chnages.

* BAEL-1226: Change for the pom

spring-rest/checkstyle.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE module PUBLIC
+          "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
+          "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">
+<module name="Checker">
+	<module name="TreeWalker">
+		<module name="AvoidStarImport">
+			<property name="severity" value="warning" />
+		</module>
+	</module>
+</module>

spring-rest/pom.xml

@@ -220,6 +220,22 @@
 				</configuration>
 			</plugin>
 		
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-checkstyle-plugin</artifactId>
+				<version>${checkstyle-maven-plugin.version}</version>
+				<configuration>
+					<configLocation>checkstyle.xml</configLocation>
+				</configuration>
+				<executions>
+					<execution>
+						<goals>
+							<goal>check</goal>
+						</goals>
+					</execution>
+				</executions>
+			</plugin>
+
 		</plugins>
 
 	</build>
@@ -311,6 +327,19 @@
 
 	</profiles>
 
+	<reporting>
+		<plugins>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-checkstyle-plugin</artifactId>
+				<version>${checkstyle-maven-plugin.version}</version>
+				<configuration>
+					<configLocation>checkstyle.xml</configLocation>
+				</configuration>
+			</plugin>
+		</plugins>
+	</reporting>
+
 	<properties>
 		<commons-fileupload.version>1.3.2</commons-fileupload.version>
 		<kryo.version>4.0.0</kryo.version>
@@ -325,7 +354,8 @@
 		<!-- Maven plugins -->
 		<cargo-maven2-plugin.version>1.6.0</cargo-maven2-plugin.version>
 		<findbugs-maven-plugin.version>3.0.4</findbugs-maven-plugin.version>
-
+		<checkstyle-maven-plugin.version>3.0.0</checkstyle-maven-plugin.version>
+		<dependency.locations.enabled>false</dependency.locations.enabled>
 		<!-- okhttp -->
 		<com.squareup.okhttp3.version>3.4.1</com.squareup.okhttp3.version>
 

spring-rest/src/main/java/org/baeldung/web/controller/HeavyResourceController.java

@@ -1,14 +1,18 @@
 package org.baeldung.web.controller;
 
 
+import java.util.Map;
+
 import org.baeldung.repository.HeavyResourceRepository;
 import org.baeldung.web.dto.HeavyResource;
 import org.baeldung.web.dto.HeavyResourceAddressOnly;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
-import org.springframework.web.bind.annotation.*;
+import org.springframework.web.bind.annotation.PathVariable;
-
+import org.springframework.web.bind.annotation.RequestBody;
-import java.util.Map;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.RestController;
 
 @RestController
 public class HeavyResourceController {

spring-rest/src/main/java/org/baeldung/web/controller/mediatypes/CustomMediaTypeController.java

@@ -2,7 +2,11 @@ package org.baeldung.web.controller.mediatypes;
 
 import org.baeldung.web.dto.BaeldungItem;
 import org.baeldung.web.dto.BaeldungItemV2;
-import org.springframework.web.bind.annotation.*;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.bind.annotation.RestController;
 
 @RestController
 @RequestMapping(value = "/", produces = "application/vnd.baeldung.api.v1+json")