simple null check: SolrCore isn't garunteed to havea CoreDescriptor, and CoreDescriptor doesn't have to have a CoreContainer
simple null check: SolrCore isn't garunteed to havea CoreDescriptor, and CoreDescriptor doesn't have to have a CoreContainer

git-svn-id: 308d55f399f3bd9aa0560a10e81a003040006c48@937529 13f79535-47bb-0310-9956-ffa450edef68

apache/solr,apache/solr,apache/solr,apache/solr,apache/solr