INT-3953: AMQP Delay Header Mapping

JIRA: https://jira.spring.io/browse/INT-3953

Polishing

Doc Polish

src/reference/asciidoc/amqp.adoc

@@ -1085,6 +1085,8 @@ Class `org.springframework.amqp.support.AmqpHeaders` identifies the default head
 
 * amqp_correlationId
 
+* amqp_delay
+
 * amqp_deliveryMode
 
 * amqp_deliveryTag
@@ -1095,6 +1097,8 @@ Class `org.springframework.amqp.support.AmqpHeaders` identifies the default head
 
 * amqp_messageId
 
+* amqp_receivedDelay
+
 * amqp_receivedExchange
 
 * amqp_receivedRoutingKey

src/reference/asciidoc/whats-new.adoc

@@ -47,7 +47,7 @@ There is a change in behavior when a POJO aggregator releases a collection of `M
 your application does that, you will need to make a small change to your POJO. See this <<agg-message-collection>> note
 for more information.
 
-==== TCP Changes
+==== TCP/UDP Changes
 
 A new `TcpConnectionServerListeningEvent` is emitted when a server connection factory is started.
 See <<tcp-events>> for more information.
@@ -74,10 +74,18 @@ See <<file-flushing>> for more information.
 
 ==== AMQP Changes
 
+===== Content Type Message Converter
+
 The outbound endpoints now support a `RabbitTemplate` configured with a `ContentTypeDelegatingMessageConverter` such
 that the converter can be chosen based on the message content type.
 See <<content-type-conversion-outbound>> for more information.
 
+===== Headers for Delayed Message Handling
+
+Spring AMQP 1.6 adds support for
+https://www.rabbitmq.com/blog/2015/04/16/scheduling-messages-with-rabbitmq/[Delayed Message Exchanges].
+Header mapping now supports the headers (`amqp_delay` and `amqp_receivedDelay`) used by this feature.
+
 ==== Redis Changes
 
 ===== List Push/Pop Direction