Polish contribution feb46fd

* Update year in license header
* Use "this" keyword where appropriate

Author: fmbenhassine

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/kafka/KafkaItemWriter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019 the original author or authors.
+ * Copyright 2019-2020 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.

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/kafka/KafkaItemWriterTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2019 the original author or authors.
+ * Copyright 2019-2020 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.
@@ -111,9 +111,9 @@ protected void writeKeyValue(String key, String value) {
 				this.kafkaTemplate.sendDefault(key, value);
 			}
 		};
-		kafkaItemWriter.setKafkaTemplate(kafkaTemplate);
+		kafkaItemWriter.setKafkaTemplate(this.kafkaTemplate);
 		kafkaItemWriter.writeKeyValue("k", "v");
-		verify(kafkaTemplate).sendDefault("k", "v");
+		verify(this.kafkaTemplate).sendDefault("k", "v");
 	}
 
 	static class KafkaItemKeyMapper implements Converter<String, String> {