AbstractAdapter::getItem() should return null, when the item cannot be retrieved
Merge branch 'version/bump'

Bump to 2.3.3dev
Fixed php 5.3 compatibility.
fix and failing testcase for custom barcode adapters in barcode object construtor
update invalid adapter exception message
Merge pull request #6576 from fabiocarneiro/hotfix-custom-barcode-validator

hotfix custom barcode adapter wasn't being set to options.
[#6576] do not use short array syntax

- as we still support 5.3.
[#6576] CS fixes (trailing whitespace)
Merge branch 'hotfix/6576' into develop

Forward port #6576
Merge branch 'cache-get-item-fix' of github.com:hver/zf2 into hver-cache-get-item-fix
Merge branch 'hver-cache-get-item-fix' into develop

Close #6560
Merge remote-tracking branch 'upstream/develop' into develop