lock-manager-impl floods logs with OptimisticLockFailedExceptions

2017-03-21 15:06:39,659 | ERROR | eChangeHandler-0 | LockManager | 351 - org.opendaylight.genius.lockmanager-impl - 0.2.0.SNAPSHOT | Unable to acquire lock, try 1
java.util.concurrent.ExecutionException: OptimisticLockFailedException

{message=Optimistic lock failed., errorList=[RpcError [message=Optimistic lock failed., severity=ERROR, errorType=APPLICATION, tag=resource-denied, applicationTag=null, info=null, cause=org.opendaylight.yangtools.yang.data.api.schema.tree.ConflictingModificationAppliedException: Node was created by other transaction.]]}

As per definition in Logging Best Practices, this should be a WARN, as there is a retry mechanism in place.

I am not familiar with the design of the lock manager, but it seems it could be using EntityOwnershipService, which already provides cluster-wide exclusive locking.

If the exceptions are direct result of application design and retries are expected, the message should be lowered to debug.