Improve @PropertyMapping error message

Improve the message thrown when a @PropertyMapping is used in
combination with a @Component to include the actual annotations that
are causing the problem.

Fixes gh-5897

spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/properties/PropertyMappingContextCustomizerFactoryTests.java

@@ -107,8 +107,9 @@ public class PropertyMappingContextCustomizerFactoryTests {
 		context.register(ConfigMapping.class);
 		customizer.customizeContext(context, null);
 		this.thrown.expect(BeanCreationException.class);
-		this.thrown.expectMessage(
-				"@PropertyMapping annotations can only be used on test classes");
+		this.thrown.expectMessage("The @PropertyMapping annotation "
+				+ "@PropertyMappingContextCustomizerFactoryTests.TypeMappingAnnotation "
+				+ "cannot be used in combination with the @Component annotation @Configuration");
 		context.refresh();
 	}