This release removes old object monitor performance counters, exposed in the `sun.rt._sync*` namespace. These counters were seldom used, and they contributed to performance problems in related VM code. Users who want to track monitor performance are advised to use related JFR events instead.

The suggested replacements are:
 - `_sync_ContendedLockAttempts`: `JavaMonitorEnter` JFR event
 - `_sync_FutileWakeups`: no replacement
 - `_sync_Parks`: `JavaMonitorWait` JFR event
 - `_sync_Notifications`: `JavaMonitorNotify` JFR event
 - `_sync_Inflations`: `JavaMonitorInflate` JFR event
 - `_sync_Deflations`: `JavaMonitorDeflate` JFR event
 - `_sync_MonExtant`: `JavaMonitorStatistics` JFR event