Second Cache Level - allow "default_multi" in region type

[orfin]

Currently it is only possible to configure "default" region type but doctrine/orm#954 introduced optimized Doctrine\ORM\Cache\Region\DefaultMultiGetRegion region that uses fetchMultiple method.

Proposal:

• allow to use "default_multi" under second_level_cache.regions.type configuration.

BTW. currently DefaultMultiGetRegion is not even documented in Doctrine docs: http://doctrine-orm.readthedocs.io/projects/doctrine-orm/en/latest/reference/second-level-cache.html#cache-regions so I'm not sure if it is production-ready?

[kimhemsoe]

Pull requests are welcome :)

[ostrolucky]

Doctrine team is contemplating switching to PSR caches in our projects. In such case this configuration would no longer be needed, as all PSR caches support multi get

[dmaicher]

From what I can tell this is obsolete now. DefaultMultiGetRegion is deprecated and the second level cache is now using PSR caches.