Unify method visibility of private classes

Apply checkstyle rule to ensure that private and package private
classes do not have unnecessary public methods. Test classes have
also been unified as much as possible to use default scoped
inner-classes.

Closes gh-7316

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/actuate/metrics/MetricsFilterBeanExample.java

@@ -29,7 +29,7 @@ import org.springframework.context.annotation.Configuration;
 public class MetricsFilterBeanExample {
 
 	@Configuration(proxyBeanMethods = false)
-	static class MetricsFilterExampleConfiguration {
+	public static class MetricsFilterExampleConfiguration {
 
 		// tag::configuration[]
 		@Bean

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/autoconfigure/UserService.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,11 +21,11 @@ package org.springframework.boot.docs.autoconfigure;
  *
  * @author Stephane Nicoll
  */
-class UserService {
+public class UserService {
 
 	private final String name;
 
-	UserService(String name) {
+	public UserService(String name) {
 		this.name = name;
 	}
 

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/autoconfigure/UserServiceAutoConfiguration.java

@@ -41,7 +41,7 @@ public class UserServiceAutoConfiguration {
 	}
 
 	@ConfigurationProperties("user")
-	static class UserProperties {
+	public static class UserProperties {
 
 		private String name = "test";
 

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/context/embedded/TomcatLegacyCookieProcessorExample.java

@@ -34,7 +34,7 @@ public class TomcatLegacyCookieProcessorExample {
 	 * Configuration class that declares the required {@link WebServerFactoryCustomizer}.
 	 */
 	@Configuration(proxyBeanMethods = false)
-	static class LegacyCookieProcessorConfiguration {
+	public static class LegacyCookieProcessorConfiguration {
 
 		// tag::customizer[]
 		@Bean

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/jdbc/BasicDataSourceExample.java

@@ -34,7 +34,7 @@ public class BasicDataSourceExample {
 	 * A configuration that exposes an empty {@link DataSource}.
 	 */
 	@Configuration(proxyBeanMethods = false)
-	static class BasicDataSourceConfiguration {
+	public static class BasicDataSourceConfiguration {
 
 		// tag::configuration[]
 		@Bean

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/jdbc/CompleteTwoDataSourcesExample.java

@@ -37,7 +37,7 @@ public class CompleteTwoDataSourcesExample {
 	 * A complete configuration that exposes two data sources.
 	 */
 	@Configuration
-	static class CompleteDataSourcesConfiguration {
+	public static class CompleteDataSourcesConfiguration {
 
 		// tag::configuration[]
 		@Bean

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/jdbc/ConfigurableDataSourceExample.java

@@ -38,7 +38,7 @@ public class ConfigurableDataSourceExample {
 	 * {@link DataSourceProperties}.
 	 */
 	@Configuration(proxyBeanMethods = false)
-	static class ConfigurableDataSourceConfiguration {
+	public static class ConfigurableDataSourceConfiguration {
 
 		// tag::configuration[]
 		@Bean

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/jdbc/SimpleDataSourceExample.java

@@ -36,7 +36,7 @@ public class SimpleDataSourceExample {
 	 * A simple configuration that exposes dedicated settings.
 	 */
 	@Configuration(proxyBeanMethods = false)
-	static class SimpleDataSourceConfiguration {
+	public static class SimpleDataSourceConfiguration {
 
 		// tag::configuration[]
 		@Bean

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/jdbc/SimpleTwoDataSourcesExample.java

@@ -40,7 +40,7 @@ public class SimpleTwoDataSourcesExample {
 	 * A simple configuration that exposes two data sources.
 	 */
 	@Configuration
-	static class SimpleDataSourcesConfiguration {
+	public static class SimpleDataSourcesConfiguration {
 
 		// tag::configuration[]
 		@Bean

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/kafka/KafkaStreamsBeanExample.java

@@ -37,7 +37,7 @@ public class KafkaStreamsBeanExample {
 	// tag::configuration[]
 	@Configuration(proxyBeanMethods = false)
 	@EnableKafkaStreams
-	static class KafkaStreamsExampleConfiguration {
+	public static class KafkaStreamsExampleConfiguration {
 
 		@Bean
 		public KStream<Integer, String> kStream(StreamsBuilder streamsBuilder) {