Ok. got the first breakthrough after all. I migrated SubQueries test.
Alan Woodward, you might be interested in noob's feedback.
Copying config folder under the given name to Zookeeper, is not obvious at all:
String configName = "solrCloudCollectionConfig";
int nodeCount = 5;
if it's possible, I ask to simplify it if possible, perhaps more descriptive names or perhaps implicit behavior, or so.
Also, I experienced a typical leg-shooting: the test had solrconfig-basic.xml w/o update log. Somewhere deep in log it was reported somehow like ERROR ... RecoveryStrategy No UpdateLog found cannot recover. It's not easier to figure out the reason looking at log tail. So, ideally there should be a circuit-breaker preventing cloud launch without updatelogs.
These two thoughts is just FYI, not really need to act.