It definitively works with Eclipse Oxygen (still), using the Updatesite from atlassian, which is also mentioned on the Bitbucket OpenSource project. Please note, the help page, which is also hosted there, offers a download link to use the updatesite offline. Since the actual data there is in fact hosted by atlassian, let's just hope they don't drop support for hosting those files.
Update Site URL: http://update.atlassian.com/atlassian-eclipse-plugin/rest/e3.7
I got the Version: 3.2.5.v20150427
As far as I can see, the support is still fully functional, including the ability to create new tickets, add comments and manage ticket lifecycle
PS: I needed to configure the proxy settings accordingly (Jira is hosted in-house here, so we need an exception rule for the proxy used for internet connection by default).