Merge pull request #30329 from PPakSang

* pr/30329:
  Update copyright year of change file
  Fix JsonSerializer example in reference guide

Closes gh-30329

spring-boot-project/spring-boot-docs/src/main/java/org/springframework/boot/docs/features/developingwebapplications/springmvc/json/MyJsonComponent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2021 the original author or authors.
+ * Copyright 2012-2022 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.
@@ -37,8 +37,10 @@ public static class Serializer extends JsonSerializer<MyObject> {
 
 		@Override
 		public void serialize(MyObject value, JsonGenerator jgen, SerializerProvider serializers) throws IOException {
+			jgen.writeStartObject();
 			jgen.writeStringField("name", value.getName());
 			jgen.writeNumberField("age", value.getAge());
+			jgen.writeEndObject();
 		}
 
 	}