Admin UI raises yellow warning "Your ZK connection string (n hosts) is different from the dynamic ensemble config (n hosts)." even when hostnames are only different by upder/lowercase.
See solr/core/src/java/org/apache/solr/handler/admin/ZookeeperStatusHandler.java method getZkStatus(String zkHost)
Method creates 2 sorted List<String> (connStringHosts and dynamicHosts) to verify the difference via containsAll, but this should be made case insensitive (e.g. by mapping the hostnames to lowercase).