The JIRA dependency has come with it's share of problems, and is currently, interwoven with blueocean-rest-impl module/plugin. 

We should consider moving things like JIRASCMListener, BlueJiraIssue to either its own plugin, externally, or possibly upstream to the JIRA plugin itself (assuming there are sufficient extension points to make use of it in blue ocean) - somehow. this means it could come with the JIRA issue or not. as it is now, it isn't easy to "turn off" if there are problem (and the user isn't using JIRA). 

Original screed (note since metrics have been excluded/made optional): 

I don't want metrics or Bitbucket or JIRA etc. installed on my instance.

It also crawled my instance to a halt, probably because the metrics plugin got installed and didn't get configured and started to loop indefinetely. Might have been something else that hogged the cpu forever, but nothing I want installed anyway.

Most of those new dependencies should be made optional.