Introduce Checkstyle rule to prohibit class names ending with "Test"

spring-context/src/test/java/example/scannable/PackageMarker.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2010 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -16,10 +16,10 @@
 
 package example.scannable;
 
-
 /**
- * Marker class for example.scannable package.
+ * Marker class for {@code example.scannable} package.
  *
  * @see org.springframework.context.annotation.ComponentScan#basePackageClasses()
  */
-public class _package { }
+public class PackageMarker {
+}

spring-context/src/test/java/org/springframework/context/annotation/ComponentScanAnnotationIntegrationTests.java

@@ -78,7 +78,7 @@ public class ComponentScanAnnotationIntegrationTests {
 	@Test
 	public void controlScan() {
 		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
-		ctx.scan(example.scannable._package.class.getPackage().getName());
+		ctx.scan(example.scannable.PackageMarker.class.getPackage().getName());
 		ctx.refresh();
 		assertThat(ctx.containsBean("fooServiceImpl")).as(
 				"control scan for example.scannable package failed to register FooServiceImpl bean").isTrue();
@@ -326,7 +326,7 @@ public class ComponentScanAnnotationIntegrationTests {
 
 
 @Configuration
-@ComponentScan(basePackageClasses = example.scannable._package.class)
+@ComponentScan(basePackageClasses = example.scannable.PackageMarker.class)
 class ComponentScanAnnotatedConfig {
 
 	@Bean
@@ -456,7 +456,7 @@ class ComponentScanWithMultipleAnnotationIncludeFilters2 {}
 @ComponentScan(
 		value = "example.scannable",
 		basePackages = "example.scannable",
-		basePackageClasses = example.scannable._package.class)
+		basePackageClasses = example.scannable.PackageMarker.class)
 class ComponentScanWithBasePackagesAndValueAlias {}