6687508: Update test/sun/management jtreg tests due to sun.management.ManagementFactory class rename
Summary: Modified the jtreg tests to use ManagementFactoryHelper instead
Reviewed-by: emcmanus
6610094: Add generic support for platform MXBeans of any type (also fixed 6681031)
Summary: Add new methods in ManagementFactory class to obtain platform MXBeans
Reviewed-by: alanb, dfuchs, emcmanus