IsStillExecutingOperation should be an urgent op. Otherwise operation itself may fail to query status of original invocation.
Added generic types to scheduler.
Migration process should use migration timeout system prop during invocation.
Replica sync responses should clear synchronization flags even when partition table changes during process.
Fixed some replica sync issues. Sync retry handling improved. All backup replicas are checked during graceful shutdown instead of just 1st.
Cleaned up BackupTest, test should rely on graceful shutdown instead of checking partition internals.
Replica sync should take max-backup count into account.
Improved some backup tests to use more nodes than max replica count.
Supress partition service method count rule
Removed an unnecessary commented line. Fixed doc typos.
Update PartitionService javadoc regarding partition safety.
Merge pull request #3940 from mdogan/fix/3.4/partition

Fixes partition problems caused by #3612