Throw IllegalStateException from afterPropertiesSet

Consistently use Assert.state in the afterPropertiesSet()
methods to throw IllegalStateException instead of
IllegalArgumentException when some properties are missing
and/or invalid.

Resolves #2244

spring-batch-integration/src/main/java/org/springframework/batch/integration/async/AsyncItemProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2019 the original author or authors.
+ * Copyright 2006-2022 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.
@@ -59,7 +59,7 @@ public class AsyncItemProcessor<I, O> implements ItemProcessor<I, Future<O>>, In
 	 * @see InitializingBean#afterPropertiesSet()
 	 */
 	public void afterPropertiesSet() throws Exception {
-		Assert.notNull(delegate, "The delegate must be set.");
+		Assert.state(delegate != null, "The delegate must be set.");
 	}
 
 	/**

spring-batch-integration/src/main/java/org/springframework/batch/integration/async/AsyncItemWriter.java

@@ -39,7 +39,7 @@ public class AsyncItemWriter<T> implements ItemStreamWriter<Future<T>>, Initiali
 	private ItemWriter<T> delegate;
 
 	public void afterPropertiesSet() throws Exception {
-		Assert.notNull(delegate, "A delegate ItemWriter must be provided.");
+		Assert.state(delegate != null, "A delegate ItemWriter must be provided.");
 	}
 
 	/**

spring-batch-integration/src/main/java/org/springframework/batch/integration/chunk/ChunkProcessorChunkHandler.java

@@ -56,7 +56,7 @@ public class ChunkProcessorChunkHandler<S> implements ChunkHandler<S>, Initializ
 	 * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet()
 	 */
 	public void afterPropertiesSet() throws Exception {
-		Assert.notNull(chunkProcessor, "A ChunkProcessor must be provided");
+		Assert.state(chunkProcessor != null, "A ChunkProcessor must be provided");
 	}
 
 	/**

spring-batch-integration/src/main/java/org/springframework/batch/integration/partition/MessageChannelPartitionHandler.java

@@ -111,7 +111,7 @@ public class MessageChannelPartitionHandler extends AbstractPartitionHandler imp
 
 	@Override
 	public void afterPropertiesSet() throws Exception {
-		Assert.notNull(stepName, "A step name must be provided for the remote workers.");
+		Assert.state(stepName != null, "A step name must be provided for the remote workers.");
 		Assert.state(messagingGateway != null, "The MessagingOperations must be set");
 
 		pollRepositoryForResults = !(dataSource == null && jobExplorer == null);

spring-batch-integration/src/test/java/org/springframework/batch/integration/async/AsyncItemProcessorTests.java

@@ -46,7 +46,7 @@ class AsyncItemProcessorTests {
 
 	@Test
 	void testNoDelegate() {
-		assertThrows(IllegalArgumentException.class, processor::afterPropertiesSet);
+		assertThrows(IllegalStateException.class, processor::afterPropertiesSet);
 	}
 
 	@Test