diff --git a/spring-integration-core/src/main/java/org/springframework/integration/filter/MessageFilter.java b/spring-integration-core/src/main/java/org/springframework/integration/filter/MessageFilter.java
index b6bcef2312a..33b9fb9fad8 100644
--- a/spring-integration-core/src/main/java/org/springframework/integration/filter/MessageFilter.java
+++ b/spring-integration-core/src/main/java/org/springframework/integration/filter/MessageFilter.java
@@ -16,6 +16,8 @@
 
 package org.springframework.integration.filter;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.context.Lifecycle;
@@ -53,9 +55,9 @@ public class MessageFilter extends AbstractReplyProducingPostProcessingMessageHa
 
 	private boolean throwExceptionOnRejection;
 
-	private MessageChannel discardChannel;
+	private  @Nullable MessageChannel discardChannel;
 
-	private String discardChannelName;
+	private  @Nullable String discardChannelName;
 
 	/**
 	 * Create a MessageFilter that will delegate to the given {@link MessageSelector}.
@@ -111,7 +113,7 @@ public void setDiscardWithinAdvice(boolean discardWithinAdvice) {
 	}
 
 	@Override
-	public MessageChannel getDiscardChannel() {
+	public  @Nullable MessageChannel getDiscardChannel() {
 		String channelName = this.discardChannelName;
 		if (channelName != null) {
 			this.discardChannel = getChannelResolver().resolveDestination(channelName);
@@ -134,15 +136,13 @@ public IntegrationPatternType getIntegrationPatternType() {
 	protected void doInit() {
 		Assert.state(!(this.discardChannelName != null && this.discardChannel != null),
 				"'discardChannelName' and 'discardChannel' are mutually exclusive.");
-		if (this.selector instanceof AbstractMessageProcessingSelector) {
+		if (this.selector instanceof AbstractMessageProcessingSelector abstractMessageProcessingSelector) {
 			ConversionService conversionService = getConversionService();
-			if (conversionService != null) {
-				((AbstractMessageProcessingSelector) this.selector).setConversionService(conversionService);
-			}
+			abstractMessageProcessingSelector.setConversionService(conversionService);
 		}
 		BeanFactory beanFactory = getBeanFactory();
-		if (this.selector instanceof BeanFactoryAware && beanFactory != null) {
-			((BeanFactoryAware) this.selector).setBeanFactory(beanFactory);
+		if (this.selector instanceof BeanFactoryAware beanFactoryAware) {
+			beanFactoryAware.setBeanFactory(beanFactory);
 		}
 	}
 
@@ -166,7 +166,7 @@ public boolean isRunning() {
 	}
 
 	@Override
-	protected Object doHandleRequestMessage(Message<?> message) {
+	protected @Nullable Object doHandleRequestMessage(Message<?> message) {
 		if (this.selector.accept(message)) {
 			return message;
 		}
diff --git a/spring-integration-core/src/main/java/org/springframework/integration/filter/MethodInvokingSelector.java b/spring-integration-core/src/main/java/org/springframework/integration/filter/MethodInvokingSelector.java
index 17a90735bc5..945dac463a5 100644
--- a/spring-integration-core/src/main/java/org/springframework/integration/filter/MethodInvokingSelector.java
+++ b/spring-integration-core/src/main/java/org/springframework/integration/filter/MethodInvokingSelector.java
@@ -34,7 +34,7 @@
 public class MethodInvokingSelector extends AbstractMessageProcessingSelector {
 
 	public MethodInvokingSelector(Object object, Method method) {
-		super(new MethodInvokingMessageProcessor<Boolean>(object, method));
+		super(new MethodInvokingMessageProcessor<>(object, method));
 		Class<?> returnType = method.getReturnType();
 		Assert.isTrue(boolean.class.isAssignableFrom(returnType)
 						|| Boolean.class.isAssignableFrom(returnType),
@@ -42,13 +42,13 @@ public MethodInvokingSelector(Object object, Method method) {
 	}
 
 	public MethodInvokingSelector(Object object, String methodName) {
-		super(new MethodInvokingMessageProcessor<Boolean>(object, methodName));
+		super(new MethodInvokingMessageProcessor<>(object, methodName));
 	}
 
 	@SuppressWarnings("unchecked")
 	public MethodInvokingSelector(Object object) {
 		super(object instanceof MessageProcessor<?> ? (MessageProcessor<Boolean>) object :
-				new MethodInvokingMessageProcessor<Boolean>(object, Filter.class));
+				new MethodInvokingMessageProcessor<>(object, Filter.class));
 	}
 
 }
diff --git a/spring-integration-core/src/main/java/org/springframework/integration/filter/package-info.java b/spring-integration-core/src/main/java/org/springframework/integration/filter/package-info.java
index 2b1d4190e67..16f44b4707d 100644
--- a/spring-integration-core/src/main/java/org/springframework/integration/filter/package-info.java
+++ b/spring-integration-core/src/main/java/org/springframework/integration/filter/package-info.java
@@ -1,4 +1,5 @@
 /**
  * Provides classes supporting the filter pattern.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.filter;
diff --git a/spring-integration-core/src/main/java/org/springframework/integration/history/HistoryWritingMessagePostProcessor.java b/spring-integration-core/src/main/java/org/springframework/integration/history/HistoryWritingMessagePostProcessor.java
index 38d28b47c85..6ea980605c3 100644
--- a/spring-integration-core/src/main/java/org/springframework/integration/history/HistoryWritingMessagePostProcessor.java
+++ b/spring-integration-core/src/main/java/org/springframework/integration/history/HistoryWritingMessagePostProcessor.java
@@ -16,6 +16,8 @@
 
 package org.springframework.integration.history;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.integration.support.DefaultMessageBuilderFactory;
 import org.springframework.integration.support.MessageBuilderFactory;
 import org.springframework.integration.support.management.TrackableComponent;
@@ -29,7 +31,7 @@
  */
 public class HistoryWritingMessagePostProcessor implements MessagePostProcessor {
 
-	private volatile TrackableComponent trackableComponent;
+	private volatile @Nullable TrackableComponent trackableComponent;
 
 	private volatile boolean shouldTrack;
 
diff --git a/spring-integration-core/src/main/java/org/springframework/integration/history/MessageHistoryConfigurer.java b/spring-integration-core/src/main/java/org/springframework/integration/history/MessageHistoryConfigurer.java
index 9bd9ab8eec8..25e10276676 100644
--- a/spring-integration-core/src/main/java/org/springframework/integration/history/MessageHistoryConfigurer.java
+++ b/spring-integration-core/src/main/java/org/springframework/integration/history/MessageHistoryConfigurer.java
@@ -63,6 +63,7 @@ public class MessageHistoryConfigurer implements ManageableSmartLifecycle, BeanF
 
 	private String[] componentNamePatterns = {"*"};
 
+	@SuppressWarnings("NullAway.Init")
 	private ListableBeanFactory beanFactory;
 
 	private boolean autoStartup = true;
diff --git a/spring-integration-core/src/main/java/org/springframework/integration/history/package-info.java b/spring-integration-core/src/main/java/org/springframework/integration/history/package-info.java
index bb452b4b98b..66452fd5155 100644
--- a/spring-integration-core/src/main/java/org/springframework/integration/history/package-info.java
+++ b/spring-integration-core/src/main/java/org/springframework/integration/history/package-info.java
@@ -1,4 +1,5 @@
 /**
  * Provides classes supporting the capture of message history.
  */
+@org.jspecify.annotations.NullMarked
 package org.springframework.integration.history;