ContentNegotiationManagerFactoryBean now provides an option to
explicitly set the strategies to use vs customizing a fixed
list of default strategies.

Issue: SPR-11114

Issue: SPR-15649

This commit moves `toEntity(Class<T>)` and `toEntityList(Class<T>)`
from WebClient.ResponseSpec to ClientResponse. The main reason for doing
so is that the newly introduced `onStatus` method (see
2f9bd6e0) does not apply to these two
methods, and the result would be confusing. Also, `ClientResponse` and
`ResponseEntity` represent the same data: status code, headers, and a
body.

Issue: SPR-15724

This commit introduces an ExchangeFilterFunction that throws an
exception given a HTTP status predicate.

Issue: SPR-15724

This commit introduces a way to customize the WebClientExceptions, as
thrown by WebClient.ResponseSpec.bodyTo[Mono|Flux]. The first
customization will override the defaults, additional customizations are
simply tried in order.

Issue: SPR-15724

This commit adds the attribute(String) convenience method to the
ClientRequest class. It also adapts the Basic Authentication filter to
use it.

This commit changes `ServerRequest.attribute(String)`` to return
`Optional<Object>` instead of `Optional<T>`, where `T` was infered
from a type parameter.

Issue: SPR-15747

Issue: SPR-15753

PathContainer now has separate parsePath and parseUrlPath methods each
creating PathSegment and UrlPathSegment respectively.

Segment.value() now returns the actual original path segment value
including path parameters while semicolonContent() is removed.

valueDecoded() is renamed to valueToMatch() to reflect it is the value
for pattern matching which is not only decoded but also has path
parameters removed.

Currently the URI path is always treated as UTF-8 so we can eliminate
the encoding parameter from RequestPath#parse.

Issue: SPR-15757

Issue: SPR-15748

Issue: SPR-15752

Issue: SPR-15154

Issue: SPR-15738

Includes page-level JSTL time zone support for JSP tags.

Issue: SPR-15720
Issue: SPR-15746

This commit makes the `uri` step of the WebTestClient optional, so that
users who have specified a base URL during WebClient config do not need
to provide an empty one (i.e. `url("")`).

Issue: SPR-15695

This commit makes the `uri` step of the WebClient optional, so that
users who have specified a base URL during WebClient config do not need
to provide an empty one (i.e. `url("")`).

The basic idea of this fix is that the HTTP method methods in WebClient
(`get`, `post`, etc.) should be able to "bypass" the uri stage, and skip
straight to defining headers, or even doing an exchange or retrieve
(i.e. call methods on `RequestHeaderSpec` or `RequestBodySpec`).

I have accomplished this by adding two new composed interfaces:
`RequestHeadersUriSpec` and `RequestBodyUriSpec`.
`RequestHeadersUriSpec` extends from the existing `UriSpec` and
`RequestHeaderSpec`, while `RequestBodyUriSpec` extends from `UriSpec`
and `RequestBodySpec`. These types are returned from the HTTP methods
(`get`, `post` etc). The `uri` methods on these types return a plain
`RequestHeaderSpec` and `RequestBodySpec` (i.e. types without the `uri`
methods), so that you can call `uri` once only.

Issue: SPR-15695

This commit introduces integration tests which verify that the
SpringExtension can be used in conjunction with JUnit Jupiter's
@ParameterizedTest support.

Issue: SPR-15742

Issue: SPR-15744

Explicitly pass the client-side JSR-356 WebSocketContainer to the
TomcatWebSocketClient to prevent the ContainerProvider from finding
the one from undertow-websockets-jsr through the ServiceLoader API.

This commit disables the "failOnServerError" feature on the
`HttpClientRequest`, as wrapped by ReactorClientHttpRequest. 5xx errors
are supposed to be dealt with in the WebClient, not in the lower-level
components.

Issue: SPR-15739