Race condition on parallel initialization of multiple solr morphlines within the same JVM

Race condition on parallel initialization of multiple solr morphlines within the same JVM. This manifests as follows in flume solr sink: If the morphlines are configured to send documents to different solr collections they might end up sending documents to the same solr collection instead.

This was reported on the mailing list here: https://groups.google.com/a/cloudera.org/forum/#!topic/search-user/Gywa1fVFixU