Sorry for lack of detail in this post - am posting from a remote location to where ocurred so don't have stack traces handy.
This problem occured in both 2.2.1 RC1 and last night when i upgraded to RC2. The effect is the failure to start of the MBean:
portal:policy=PortalPolicyConfigStore,type=Component
In both cases I have found that I can circumvent the problem by changing the MBean config from
<depends optional-attribute-name="CacheProvider" proxy-type="attribute">portal:service=TreeCacheProvider,type=transient</depends>
<depends optional-attribute-name="CacheProvider" proxy-type="attribute">portal:service=TreeCacheProvider,type=persistent</depends>