Enhancement Proposal: *Context.cacheControl()

[mkarg]

Recently we deprecated CacheControl.valueOf(String), but the replacement is a rather clumsy code line: RuntimeDelegate.getInstance().createHeaderDelegate(CacheControl.class).fromString(value). This is very annoying e. g. when migrating filters from 2.x to 3.x.

To make the programmer's life easier, I like to propose that we add support for some syntactic sugar:

• Add new method cacheControl() on Client/Server Request/Response Context returning a modifiable instance of CacheControl initialized by the content of the Cache-Control header.