When restarting Jira, Xray may be disabled (CachingCustomFieldManager)

When restarting Jira, Xray won't be enabled.

When restarting Jira, Xray fails to enable due to a nullpointer coming from the CachingCustomFieldManager. After the Jira instance is up, it is then possible to manually enable Xray (although it will be disabled again the next time Jira restarts).

There is a workaround currently in place for this issue, consisting of delaying the startup of Xray until after the other plugins have started up.