Fix compiler warnings

- Add `@Nullable` where needed
- Suppress warnings where appropriate
- Add generic type definitions

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

@@ -99,6 +99,7 @@ public class ChunkProcessorChunkHandler<S> implements ChunkHandler<S>, Initializ
 	 * @param stepContribution the step contribution to update
 	 * @throws Exception if there is a fatal exception
 	 */
+	@SuppressWarnings(value = { "unchecked", "rawtypes" })
 	private Throwable process(ChunkRequest<S> chunkRequest, StepContribution stepContribution) throws Exception {
 
 		Chunk chunk = chunkRequest.getItems();

spring-batch-integration/src/main/java/org/springframework/batch/integration/config/annotation/BatchIntegrationConfiguration.java

@@ -34,7 +34,7 @@ import org.springframework.transaction.PlatformTransactionManager;
  * @author Mahmoud Ben Hassine
  */
 @Configuration(proxyBeanMethods = false)
-public class BatchIntegrationConfiguration implements InitializingBean {
+public class BatchIntegrationConfiguration<I, O> implements InitializingBean {
 
 	private final JobExplorer jobExplorer;
 
@@ -44,7 +44,7 @@ public class BatchIntegrationConfiguration implements InitializingBean {
 
 	private RemoteChunkingManagerStepBuilderFactory remoteChunkingManagerStepBuilderFactory;
 
-	private RemoteChunkingWorkerBuilder remoteChunkingWorkerBuilder;
+	private RemoteChunkingWorkerBuilder<I, O> remoteChunkingWorkerBuilder;
 
 	private RemotePartitioningManagerStepBuilderFactory remotePartitioningManagerStepBuilderFactory;
 
@@ -65,7 +65,7 @@ public class BatchIntegrationConfiguration implements InitializingBean {
 	}
 
 	@Bean
-	public <I, O> RemoteChunkingWorkerBuilder<I, O> remoteChunkingWorkerBuilder() {
+	public RemoteChunkingWorkerBuilder<I, O> remoteChunkingWorkerBuilder() {
 		return remoteChunkingWorkerBuilder;
 	}
 

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

@@ -286,6 +286,7 @@ public class MessageChannelPartitionHandler extends AbstractPartitionHandler imp
 		}
 	}
 
+	@SuppressWarnings("unchecked")
 	private Set<StepExecution> receiveReplies(PollableChannel currentReplyChannel) {
 		Message<Set<StepExecution>> message = (Message<Set<StepExecution>>) messagingGateway
 			.receive(currentReplyChannel);