[xwiki-users] debian xwiki-solr-data package

Hi, I'm still struggling to get XWiki installed on Ubuntu 16.06 using theDebian packages. :-( I see on http://platform.xwiki.org/xwiki/bin/view/AdminGuide/InstallationViaAPT that there is a package xwiki-solr-data that appears to be optional (at least, it isn't installed as a dependent package with xwiki-enterprise-tomcat8-pgsql). Is this actually a required package? I ask because my Tomcat logs have a lot of entries like 2016-08-22 03:51:44,753 [coreLoadExecutor-6-thread-1] WARN o.a.s.c.SolrCore - [xwiki] Solr index directory '/var/lib/xwiki/data/solr/xwiki/data/index' doesn't exist. Creating new index... 2016-08-22 03:51:45,544 [coreLoadExecutor-6-thread-1] WARN o.i.j.ResourceDMBean - ISPN000042: Did not find queried attribute with name coreHashCode [...snip...] 2016-08-22 03:51:45,607 [coreLoadExecutor-6-thread-1] ERROR o.a.s.c.CoreContainer - Error creating core [xwiki]: Error opening new searcher org.apache.solr.common.SolrException: Error opening new searcher [etc]