diff --git a/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/AbstractNamedValueMethodArgumentResolver.java b/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/AbstractNamedValueMethodArgumentResolver.java
index 09c97aff6ae3e1a13589ffa02182fd0fab87246f..de31ebee247960620e5cf92be1536a5c74979d10 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/AbstractNamedValueMethodArgumentResolver.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/AbstractNamedValueMethodArgumentResolver.java
@@ -73,10 +73,16 @@ public abstract class AbstractNamedValueMethodArgumentResolver implements Handle
 	 * @param beanFactory a bean factory for resolving {@code ${...}}
 	 * placeholders and {@code #{...}} SpEL expressions in default values
 	 */
-	protected AbstractNamedValueMethodArgumentResolver(@Nullable ConversionService conversionService,
+	protected AbstractNamedValueMethodArgumentResolver(ConversionService conversionService,
 			@Nullable ConfigurableBeanFactory beanFactory) {
 
-		this.conversionService = conversionService != null ? conversionService : DefaultConversionService.getSharedInstance();
+		// Fallback on shared ConversionService for now for historic reasons.
+		// Possibly remove after discussion in gh-23882.
+
+		//noinspection ConstantConditions
+		this.conversionService = conversionService != null ?
+				conversionService : DefaultConversionService.getSharedInstance();
+
 		this.configurableBeanFactory = beanFactory;
 		this.expressionContext = (beanFactory != null ? new BeanExpressionContext(beanFactory, null) : null);
 	}
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/DestinationVariableMethodArgumentResolver.java b/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/DestinationVariableMethodArgumentResolver.java
index e0e4e16e0b7e146557c96e70a79c812c182cdbc8..ad80d5922dc12add1baec5a52a9502940c040eee 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/DestinationVariableMethodArgumentResolver.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/DestinationVariableMethodArgumentResolver.java
@@ -41,7 +41,7 @@ public class DestinationVariableMethodArgumentResolver extends AbstractNamedValu
 			DestinationVariableMethodArgumentResolver.class.getSimpleName() + ".templateVariables";
 
 
-	public DestinationVariableMethodArgumentResolver(@Nullable ConversionService conversionService) {
+	public DestinationVariableMethodArgumentResolver(ConversionService conversionService) {
 		super(conversionService, null);
 	}
 
diff --git a/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolver.java b/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolver.java
index a3a21d53016cf62b76c2d4547b5671532e356866..e6b50f058631ccb66a3abf281604ac93f6f80822 100644
--- a/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolver.java
+++ b/spring-messaging/src/main/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolver.java
@@ -49,7 +49,7 @@ public class HeaderMethodArgumentResolver extends AbstractNamedValueMethodArgume
 
 
 	public HeaderMethodArgumentResolver(
-			@Nullable ConversionService conversionService, @Nullable ConfigurableBeanFactory beanFactory) {
+			ConversionService conversionService, @Nullable ConfigurableBeanFactory beanFactory) {
 
 		super(conversionService, beanFactory);
 	}
diff --git a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolverTests.java b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolverTests.java
index fcc4772a070d8a60f6c716667bb29083505eebef..503ef454ed8248cea64d0459cf86a9f29aa747ac 100644
--- a/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolverTests.java
+++ b/spring-messaging/src/test/java/org/springframework/messaging/handler/annotation/support/HeaderMethodArgumentResolverTests.java
@@ -145,14 +145,6 @@ public class HeaderMethodArgumentResolverTests {
 		assertThat(result).isEqualTo(Optional.of("bar"));
 	}
 
-	@Test
-	public void resolveOptionalHeaderWithValueFromNullConversionServiceInput() throws Exception {
-		GenericApplicationContext context = new GenericApplicationContext();
-		context.refresh();
-		resolver = new HeaderMethodArgumentResolver(null, context.getBeanFactory());
-		resolveOptionalHeaderWithValue();
-	}
-
 	@Test
 	public void resolveOptionalHeaderAsEmpty() throws Exception {
 		Message<String> message = MessageBuilder.withPayload("foo").build();