Upgrade to checkstyle 8.21

Closes gh-113

Author: philwebb

pom.xml

@@ -38,6 +38,7 @@
 		<ant-contrib.version>1.0b3</ant-contrib.version>
 		<asm.version>5.2</asm.version>
 		<assertj.version>3.8.0</assertj.version>
+		<checkstyle.version>8.21</checkstyle.version>
 		<gradle.version>3.4</gradle.version>
 		<groovy.version>2.4.7</groovy.version>
 		<maven-core.version>3.5.0</maven-core.version>
@@ -86,7 +87,7 @@
 						<dependency>
 							<groupId>com.puppycrawl.tools</groupId>
 							<artifactId>checkstyle</artifactId>
-							<version>8.21</version>
+							<version>${checkstyle.version}</version>
 						</dependency>
 					</dependencies>
 				</plugin>
@@ -472,7 +473,7 @@
 			<dependency>
 				<groupId>com.puppycrawl.tools</groupId>
 				<artifactId>checkstyle</artifactId>
-				<version>8.18</version>
+				<version>${checkstyle.version}</version>
 			</dependency>
 			<dependency>
 				<groupId>net.sf.trove4j</groupId>

spring-javaformat/spring-javaformat-checkstyle/src/main/java/io/spring/javaformat/checkstyle/SpringChecks.java

@@ -47,10 +47,6 @@
  */
 public class SpringChecks extends AbstractFileSetCheck implements ExternalResourceHolder {
 
-	private static final int DEFAULT_TAB_WIDTH = 8;
-
-	private int tabWidth = DEFAULT_TAB_WIDTH;
-
 	private ClassLoader classLoader;
 
 	private ModuleFactory moduleFactory;
@@ -65,14 +61,6 @@ public class SpringChecks extends AbstractFileSetCheck implements ExternalResour
 
 	private String projectRootPackage = SpringImportOrderCheck.DEFAULT_PROJECT_ROOT_PACKAGE;
 
-	/**
-	 * Sets tab width.
-	 * @param tabWidth the distance between tab stops
-	 */
-	public void setTabWidth(int tabWidth) {
-		this.tabWidth = tabWidth;
-	}
-
 	/**
 	 * Sets classLoader to load class.
 	 * @param classLoader class loader to resolve classes with.
@@ -94,7 +82,7 @@ public void finishLocalSetup() {
 		DefaultContext context = new DefaultContext();
 		context.add("classLoader", this.classLoader);
 		context.add("severity", getSeverity());
-		context.add("tabWidth", String.valueOf(this.tabWidth));
+		context.add("tabWidth", String.valueOf(getTabWidth()));
 		context.add("moduleFactory", this.moduleFactory);
 		Properties properties = new Properties();
 		put(properties, "headerType", this.headerType);