sockjs-client expects a prelude to be written on every request with
streaming transports. The protocol tests don't make this clear and
don't expose this issue.

The test case for SPR-11183 (writing 20K messages in succession) did
expose the issue and this commit addresses it.

Issue: SPR-11183

Introduced customizeConnection callbacks for URLConnection used by exists() / contentLength() / lastModified()

Issue: SPR-11320

Issue: SPR-11319

Issue: SPR-8182
Issue: SPR-11243
Issue: SPR-11292
Issue: SPR-11318

Issue: SPR-11314

Issue: SPR-11317

Introduced "globalInitializerClasses" next to the existing "contextInitializerClasses", applying to FrameworkServlets as well

Issue: SPR-11314

Issue: SPR-11297

Fixed getTypeDifferenceWeight algorithm in ReflectionHelper, and removed unused argsRequiringConversion storage

Issue: SPR-11306

Issue: SPR-11237

Issue: SPR-11256

Issue: SPR-11301

Better integrated explanation of the 'default' profile with both XML
and Java config examples showing the same thing.

Issue: SPR-11256

Issue: SPR-11307

When adding headers generically, MockHttpServletRequestBuilder now
recognizes Content-Type and updates the contentType field accordingly.

Issue: SPR-11308

Also making 'description' available on SimpleTriggerFactoryBean.

Issue: SPR-9771
(cherry picked from commit 7502ecd3)

This change adds a protected method to DefaultHandshakeHandler to
determine the user for the WebSocket session. By default it's
implemeted to obtain it from the request.

Issue: SPR-11228

The Jetty ServletWebUpgradeRequest implements getUserPrincipal to
return the Principal from the HttpServletRequest on the upgrade.
This change ensures we can fall back on that.

However the JettyRequestUpgradeStrategy still passes the user from
HttpServletRequest from the upgrade, in order to work with Jetty
9.0.x and avoid running into this 9.1.x issue:

https://bugs.eclipse.org/bugs/show_bug.cgi?id=423118

Issue: SPR-11299

This is short to avoid having to use MockMvcRequestBuilders.request()
and instead have a simple patch(url, params...)