JMX MBeans disappear sometimes when validation is enabled. Reproducer steps are on WFLY-2551.
Fix is to backport https://github.com/wildfly/wildfly/commit/0a59f93cae431bf952877b505856b49c7f839603 and https://github.com/wildfly/wildfly/commit/b6cf66cfc26aadd568c69f4f325c993f374c03f7
QA: reproducer steps are on WFLY-2551
verified on EAP 6.4.0.DR11