The addition of SubProtocolCapable simplifies configuration since it is
no longer necessary to explicitly configure DefaultHandshakeHandler
with a list of supported sub-protocols. We will not also check if the
WebSocketHandler to use for the WebSocket request is an instance of
SubProtocolCapable and obtain the list of sub-protocols that way. The
provided SubProtocolWebSocketHandler does implement this interface.

Issue: SPR-11111

Fix remaining Java compiler warnings, mainly around missing
generics or deprecated code.

Also add the `-Werror` compiler option to ensure that any future
warnings will fail the build.

Issue: SPR-11064

Before this change spring-messaging contained a few WebSocket-related
classes including WebSocket sub-protocol support for STOMP as well
as @EnableWebSocketMessageBroker and related configuration classes.

After this change those classes are located in the spring-websocket
module under org.springframework.web.socket.messaging.

This means the following classes in application configuration must
have their packages updated:

org.springframework.web.socket.messaging.config.EnableWebSocketMessageBroker
org.springframework.web.socket.messaging.config.StompEndpointRegistry
org.springframework.web.socket.messaging.config.WebSocketMessageBrokerConfigurer

MessageBrokerConfigurer has been renamed to MessageBrokerRegistry and
is also located in the above package.

Before this change the amount of logging was too little or too much
with TRACE turned on. This change separates useful debugging
information and logs it under DEBUG and leaves more detailed
information to be logged under TRACE.

The SockJS path is now passed to the SockJsService handleRequest method
thus removing the need to guess it.

Issue: SPR-11058

GenericTypeResolver's resolveTypeArguments needs to return null for raw types (for backwards compatibility with 3.2)

Issue: SPR-11052

This changes switches from using Jetty's WebSocketListener interface
to use Jetty's @WebSocket annotations instead. The change should be
transparent but the annnotations provide a little more controler
including handling pong frames.

This change also introduces a WebSocketMessage interface.

Issue: SPR-10877

This commit upgrades Jetty to the latest available 9.1.x version while
also preserving compatibility with 9.0.x.

- Removed unused imports
- Organized imports
- Deleted unused fields
- Deleted unused local variables
- Deleted unused private static classes

- add WebSocketHttpHeaders
- client-side support for WebSocket extensions
- DefaultHandshakeHandler updates
- replace use of ServletAttributes in JettyRequestUpgradeStratey
- upgrade spring-web to jetty 9.0.5

This commits adds simple, overridable WebSocket Extension
filtering during the handshake phase and adds that
information in the WebSocket session.

The actual WebSocket Extension negotiation happens
within the server implementation (Glassfish, Jetty, Tomcat...),
so one can only remove requested extensions from
the list provided by the WebSocket client.

See RFC6455 Section 9.

Issue: SPR-10843

Issue: SPR-10893

Issue: SPR-10923

Issue: SPR-10854

Commit 2397b210 changed websocket
support to use GlassFish 4.0.1 nightlies, but broke support for 4.0. In
GlassFish 4.0.1, the package that TyrusEndpoint is located in changed.
This commit provides an abstract handler that does all required
GlassFish setup, but delegates to version specific upgrade handlers to
create the final TyrusEndpoint.

GlassFish 4.0 handler uses reflection to create its endpoint to prevent
dependency issues of depending on different versions of
tyrus-websocket-core and tyrus-container-servlet

Issue: SPR-10939

Issue: SPR-10888

Issue: SPR-10703

After this change, annotated message handling methods configured to use
a destination prefix (e.g. "/app") no longer have to include the prefix
in their mapping. For example if a client sends a message to "/app/foo"
the annotated methods should be mapped with @MessageMapping("/foo").

Ensure configuration provided for WebSocketHandler's (eg interceptors,
or HandshakeHandler) are passed on to the SockJsService if congiured.

Better separate Servlet-specific parts of the configuration to make it
more obvious where non-Servlet alternatives could fit in.

Add more tests.

Improve WebSocket integration tests.

Issue: SPR-10880

Issue: SPR-10876

Issue: SRP-10868

Issue: SPR-10605

Issue: SPR-10835

Issue: SPR-10835

Issue: SPR-10861

Issue: SPR-10844

First try the endpoint type name converted to property
Then try @Component value

Issue: SPR-10605

While RC2 is not yet out, we need to support RC1 as well.
This change introduces temporary code that can be removed
once RC2 becomes available to avoid having to use Tomcat
snapshots.

This targets currently nightly snapshots and future release
of Glassfish 4.0.1.

After this change the DefaultHandshakeHandler delegates to a
server-specific RequestUpgradeStrategy to update the HTTP response for
the handshake request and to begin the WebSocket interaction.

The DefaultHandshakeHandler however still retains the initial
validation of the WebSocket handshake including negotation of origin,
sub-protocol, etc. This allows sub-classes to override various
aspects of the negotiation independant of the WebSocket engine.

In addition to implementing ServerEndpointConfig, the
ServerEndpointRegistration now also extends
ServerEndpointConfig.Configurator making it easier to override
handshake customization methods without having to extend a separate
class.