GH-3006: Read x-death count in a safer way

Fixes: #3006

We had an issue in our system trying to consume a message from RabbitMQ that contained an `x-death` header, with count value typed as `Integer`. 
This caused a `ClassCastException`.
The reason the count value was an int and not a long is that we were storing headers in an internal database as part of a recovery process, and the typing was slightly changed during serialisation / deserialisation.

* Use  `target.setRetryCount(numberValue.longValue());` in the `DefaultMessagePropertiesConverter` instead of cast to `long`

Signed-off-by: Raul Avila <[email protected]>

[[email protected] Improve commit message]

**Auto-cherry-pick to `3.2.x`**

Signed-off-by: Artem Bilan <[email protected]>

Author: raul-avila-ph

spring-rabbit/src/main/java/org/springframework/amqp/rabbit/support/DefaultMessagePropertiesConverter.java

@@ -44,6 +44,7 @@
  * @author Artem Bilan
  * @author Ngoc Nhan
  * @author Johan Kaving
+ * @author Raul Avila
  *
  * @since 1.0
  */
@@ -147,7 +148,11 @@ else if (MessageProperties.RETRY_COUNT.equals(key)) {
 		if (target.getRetryCount() == 0) {
 			List<Map<String, ?>> xDeathHeader = target.getXDeathHeader();
 			if (!CollectionUtils.isEmpty(xDeathHeader)) {
-				target.setRetryCount((long) xDeathHeader.get(0).get("count"));
+				Object value = xDeathHeader.get(0).get("count");
+
+				if (value instanceof Number numberValue) {
+					target.setRetryCount(numberValue.longValue());
+				}
 			}
 		}
 

spring-rabbit/src/test/java/org/springframework/amqp/rabbit/support/DefaultMessagePropertiesConverterTests.java

@@ -104,6 +104,21 @@ public void testToMessagePropertiesLongStringInMap() {
 		assertThat(((Map<String, Object>) messageProperties.getHeaders().get("map")).get("longString")).as("LongString nested in Map not converted to String").isEqualTo(longStringString);
 	}
 
+	@Test
+	public void testToMessagePropertiesXDeathCount() {
+		Map<String, Object> headers = new HashMap<String, Object>();
+
+		headers.put("x-death", List.of(Map.of("count", Integer.valueOf(2))));
+
+		BasicProperties source = new BasicProperties.Builder()
+				.headers(headers)
+				.build();
+
+		MessageProperties messageProperties = messagePropertiesConverter.toMessageProperties(source, envelope, "UTF-8");
+
+		assertThat(messageProperties.getRetryCount()).isEqualTo(2);
+	}
+
 	@Test
 	public void testLongLongString() {
 		Map<String, Object> headers = new HashMap<String, Object>();