From 96c627d0b60da3faee9d8319ecb334eccd141a05 Mon Sep 17 00:00:00 2001
From: anjeongkyun <anwjdrbs123@gmail.com>
Date: Sun, 13 Sep 2026 15:57:51 +0900
Subject: [PATCH] Do not put a null message attribute when contentType is
 unsupported

getContentTypeMessageAttribute returns null for a contentType header that is
neither a MimeType nor a String, and the caller put that null straight into the
attribute map. The SDK then fails marshalling the whole publish request.
Fall back to the same warn-and-skip the loop already uses for header types SNS
cannot carry.
---
 .../sns/core/SnsHeaderConverterUtil.java      | 20 ++++++++++++++-----
 .../sns/core/TopicMessageChannelTest.java     | 16 +++++++++++++++
 2 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/spring-cloud-aws-sns/src/main/java/io/awspring/cloud/sns/core/SnsHeaderConverterUtil.java b/spring-cloud-aws-sns/src/main/java/io/awspring/cloud/sns/core/SnsHeaderConverterUtil.java
index 388c70029c..f6783e29c6 100644
--- a/spring-cloud-aws-sns/src/main/java/io/awspring/cloud/sns/core/SnsHeaderConverterUtil.java
+++ b/spring-cloud-aws-sns/src/main/java/io/awspring/cloud/sns/core/SnsHeaderConverterUtil.java
@@ -60,7 +60,13 @@ public static Map<String, MessageAttributeValue> toSnsMessageAttributes(Message<
 			}
 
 			if (MessageHeaders.CONTENT_TYPE.equals(messageHeaderName) && messageHeaderValue != null) {
-				messageAttributes.put(messageHeaderName, getContentTypeMessageAttribute(messageHeaderValue));
+				MessageAttributeValue contentType = getContentTypeMessageAttribute(messageHeaderValue);
+				if (contentType != null) {
+					messageAttributes.put(messageHeaderName, contentType);
+				}
+				else {
+					logUnsupportedHeader(messageHeaderName, messageHeaderValue);
+				}
 			}
 			else if (MessageHeaders.ID.equals(messageHeaderName) && messageHeaderValue != null) {
 				messageAttributes.put(messageHeaderName, getStringMessageAttribute(messageHeaderValue.toString()));
@@ -81,16 +87,20 @@ else if (messageHeaderValue instanceof List) {
 				messageAttributes.put(messageHeaderName, getStringArrayMessageAttribute((List<?>) messageHeaderValue));
 			}
 			else {
-				logger.warn(String.format(
-						"Message header with name '%s' and type '%s' cannot be sent as"
-								+ " message attribute because it is not supported by SNS.",
-						messageHeaderName, messageHeaderValue != null ? messageHeaderValue.getClass().getName() : ""));
+				logUnsupportedHeader(messageHeaderName, messageHeaderValue);
 			}
 		}
 
 		return messageAttributes;
 	}
 
+	private static void logUnsupportedHeader(String messageHeaderName, @Nullable Object messageHeaderValue) {
+		logger.warn(String.format(
+				"Message header with name '%s' and type '%s' cannot be sent as"
+						+ " message attribute because it is not supported by SNS.",
+				messageHeaderName, messageHeaderValue != null ? messageHeaderValue.getClass().getName() : ""));
+	}
+
 	private static boolean isSkipHeader(String headerName) {
 		return NOTIFICATION_SUBJECT_HEADER.equals(headerName) || MESSAGE_GROUP_ID_HEADER.equals(headerName)
 				|| MESSAGE_DEDUPLICATION_ID_HEADER.equals(headerName);
diff --git a/spring-cloud-aws-sns/src/test/java/io/awspring/cloud/sns/core/TopicMessageChannelTest.java b/spring-cloud-aws-sns/src/test/java/io/awspring/cloud/sns/core/TopicMessageChannelTest.java
index e587a8b100..00251ba4b3 100644
--- a/spring-cloud-aws-sns/src/test/java/io/awspring/cloud/sns/core/TopicMessageChannelTest.java
+++ b/spring-cloud-aws-sns/src/test/java/io/awspring/cloud/sns/core/TopicMessageChannelTest.java
@@ -211,6 +211,22 @@ void sendMessage_withStringArrayMessageHeader_shouldBeSentAsTopicMessageAttribut
 		}));
 	}
 
+	@Test
+	void sendMessage_withUnsupportedContentTypeHeader_shouldNotSetItAsMessageAttribute() {
+		// Arrange
+		// a contentType that is neither a MimeType nor a String
+		Message<String> message = MessageBuilder.withPayload("Hello")
+				.setHeader(MessageHeaders.CONTENT_TYPE, new Object()).build();
+
+		// Act
+		boolean sent = messageChannel.send(message);
+
+		// Assert
+		assertThat(sent).isTrue();
+		verify(snsClient).publish(requestMatches(
+				it -> assertThat(it.messageAttributes()).doesNotContainKey(MessageHeaders.CONTENT_TYPE)));
+	}
+
 	@Test
 	void sendMessage_withMessageGroupIdHeader_shouldSetMessageGroupIdOnPublishRequestAndNotSetItAsMessageAttribute() {
 		// Arrange