Issue: SPR-12730

Issue: SPR-12724

Issue: SPR-12724

Issue: SPR-12655

Prior to this change when adding subscriptions
DefaultSubscriptionRegistry (incorrectly) made a copy of the given map
for its "access" cache rather than for its "update" cache.

Issue: SPR-12665

This change removes the need for the isStreaming field from the base
class AbstractHttpSockJsSession. This field was used to account for
differences between polling vs streaming SockJS sessions without having
to expose to sub-classes private fields that are otherwise protected
from concurrent access by the base class. The change manages to delegate
to sub-classes without providing direct access to protected fields.

Issue: SPR-12427

Issue: SPR-12567

With this commit, Jackson builder is now used in spring-websocket
to create the ObjectMapper instance.

It is not possible to use the builder for spring-messaging
and spring-jms since these modules don't have a dependency on
spring-web, thus they now just customize the same features:
 - MapperFeature#DEFAULT_VIEW_INCLUSION is disabled
 - DeserializationFeature#FAIL_ON_UNKNOWN_PROPERTIES is disabled

Issue: SPR-12293

Issue: SPR-12479

Issue: SPR-12484

Issue: SPR-12431

Issue: SPR-12406

This commit fixes the parsing of message destinations such as
"/user/anna/queue/foo", reverting a regression introduced by SPR-11506,
which worked well with @SendToUser use cases but caused issues for
messages sent to other users.

Issue: SPR-12444

Issue: SPR-12418

Before this change the simple broker simply removed subscriptions
upon receiving a DISCONNECT message assuming it was a result of
a client STOMP WebSocket session ending.

However, if the server-side application sends a DISCONNECT to
the broker in order to terminate a session, the STOMP WebSocket
session could remain unware without any further action. This
change ensures the simple broker sends a DISCONNECT_ACK message
downstream whenever it receives a DISCONNECT.

Issue: SPR-12288

This change adds a ChannelInterceptor that flips the immutable flag on
messages being sent. This allows components sending messages to leave
the message mutable for interceptors to further apply modifications
before the message is sent (and exposed to concurrency).

The interceptor is automatically added with the STOMP/WebSocket Java
and XML config and the StompSubProtocolHandler leaves parsed incoming
messages mutable so they can be further modified before being sent.

Issue: SPR-12321

AbstractMessageChannel triggers afterSendCompletion with previously resolved non-null Message in case of preSend returning null

Issue: SPR-12295

Issue: Issue: SPR-12272

Issue: SPR-12272

Issue: SPR-12272

Consolidate inner classes used to invoke a subscriber with
interceptors.

Issue: SPR-12218

The new contract allows registration of interceptors with any
MessageChannel implementation hierarchy -- for example the one in the
Spring Framework or the one in Spring Integration.

When a DISCONNECT is sent to the broker, we proactively close the TCP
connection unless the DISCONNECT has a receipt header. Depending on
the timing, the broker may also close the connection on its side.
That appears to cause an exception in reactor on the CI server, e.g.:

https://build.spring.io/browse/SPR-PUB-JOB1-1715/test/case/135247530

This change traps the exceptions and prevents it from propagating.

This change uses a ChannelInterceptor (inserted at index 0) to detect
when a DISCONNECT message is precluded from being sent on the
clientInboundChannel. This can happen if another interceptor allows
a runtime exception out from preSend or returns false.

It is crucial for such messages to be processed, so when detected
they're processed still.

Issue: SPR-12218

Issue: SPR-12249