grails/grails-core — comment on commit 53a0439ad6caf028526e0cf33756ec5ff4550407
File:  line 0
By burtbeckwith:

The purpose of the new Holder and Holders classes was to create a way to have non-static access to singleton objects like ApplicationHolder, etc. The approach used is to maintain a static map keyed by classloader, so multiple applications deployed in a contained using shared jars will each have their own. This isn't finished yet, so there's still fallback code to use the traditional holders. I removed the error message since it implies there's an error, which is technically true since the new implementation isn't working correctly, but in practice not true since in the worst case it behaves like it did before.

The Spring Security Core plugin issue is separate and due to an interaction with the resources plugins - I'll fix that soon.