Closes gh-14927

* gh-14912:
  Use Errors.hasErrors() in DefaultErrorAttributes

Closes gh-14912

* gh-14916:
  Avoid creation of unnecessary collections

Closes gh-14916

Fix `ResourceUrlEncodingFilter` conditions which were inadvertently
changed in commits 64f04fce and 6cc272ec and would back off if any
`FilterRegistrationBean` was found.

The updated conditions restores the behavior of Spring Boot 2.0.5 and
allows users to directly register their own `ResourceUrlEncodingFilter`
beans (as long as they don't use a `FilterRegistrationBean`).

Fixes gh-14897

This commit also marks a release as pre-release for milestones and RCs

Closes gh-14908
Closes gh-14875

Closes gh-14872

See gh-14893

Previously, when using Tomcat, a call to mappings endpoint would force
the initialization of any DispatcherServlets in the context. This was
done by calling allocate on Tomcat's StandardWrapper. This left the
wrapper in a state that would cause it to block for two seconds during
shutdown as the wrapper has an outstanding allocation.

This commit immediately deallocates the servlet after it has been
allocated. This ensures that the DispatcherServlet has been initialized
while also leaving the wrapper in a state that it can shut down
immediately when asked to do so.

Closes gh-14898

Closes gh-14878

Closes gh-14851

* pr/14836:
  Force JMX hostname to 127.0.0.1

Closes gh-14836

See gh-14857

This commit also restores the `sed` call to sanitize the request body.

Fixes gh-14857

Closes gh-14503

See gh-14843

Closes gh-14833

Closes gh-14850

Closes gh-14732

Closes gh-14848

Deprecate `SecurityPrerequisite` interface since we don't support it
in Spring Boot 2.

Closes gh-14846

Closes gh-14454