Clarified ArgsMatchKind deprecation
Removed Commons Lang references and refined Java 5+ implementation details
Introduced "spring.getenv.ignore" system property for preventing System.getenv calls

Issue: SPR-11297
(cherry picked from commit 961f42b)
Polishing
(cherry picked from commit e670f4e)
Introduced "globalInitializerClasses" next to the existing "contextInitializerClasses", applying to FrameworkServlets as well

Issue: SPR-11314
(cherry picked from commit 91881ff)
Polishing
checkNotModified needs to consider HEAD as well

Issue: SPR-11317
(cherry picked from commit 17cc63e)
Fixed accidental use of String.isEmpty in SimpleCommandLineArgsParser

Issue: SPR-11321
Polishing
Introduced customizeConnection callbacks for URLConnection used by exists() / contentLength() / lastModified()

Issue: SPR-11320
(cherry picked from commit 4f45ad5)
Polishing