Using zabbix to monitor my Solr instance I noticed that after core reloading the Mbeans have disappeared. There is a test -> testJmxIntegration#testJmxOnCoreReload used to check Mbeans presence after core reload. The test is wrong because TestHarness sets core name to null on creating the core for the first time (CoreContainer#initialize) so his Mbeans have jmxRootName="solr" (JmxMonitoredMap#line61). Once the core is created it sets coreName = "" causing new Mbeans to have jmxRootName="solr/"
So after first core closing only MBeans having name "solr" are removed and only MBeans with name "solr/" persists on JMXServer. This test is fake.
Step to reproduce test fail
1) Apply TestHarness patch
2) Run the tests