Add @FunctionalInterface to ChunkProcessor

Author: pongdangx2

spring-batch-core/src/main/java/org/springframework/batch/core/step/item/ChunkProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2022 the original author or authors.
+ * Copyright 2006-2025 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.
@@ -22,8 +22,10 @@
 /**
  * Interface defined for processing {@link org.springframework.batch.item.Chunk}s.
  *
+ * @author Kyeonghoon Lee
  * @since 2.0
  */
+@FunctionalInterface
 public interface ChunkProcessor<I> {
 
 	void process(StepContribution contribution, Chunk<I> chunk) throws Exception;