If a global component fails to start during cache startup, future getCache calls for that cache will never return

In DefaultCacheManager, before starting a cache we register a CacheWrapper with the cache name, and subsequent calls to getCache(cacheName) will wait for a countdown latch in the CacheWrapper to confirm that the cache has finished starting.

However, if a global component fails to start, that latch is never opened - so future calls to getCache(cacheName) will block forever.

If startCaches() is used to start multiple caches at once, the global start exception will be on a background thread and the user will only notice that the getCache calls on the main thread never return.

This situation appeared in the hibernate-search test suite, which extended JGroupsTransport to change the cluster name to a unique value on startup. The cluster name is not dynamic in 5.1, so the global component registry failed to start.