public long startOperation() {
    return operationMonitor.startOperation();
  }
this method must be invoked at the start of every operation that can modify the state of
resource. The return value must be recorded and sent to the advisor in an endOperation message
when messages for the operation have been put in the DistributionManager's outgoing "queue".

@return the current membership version for this advisor
@since GemFire 5.1
geode-core/src/main/java/org/apache/geode/distributed/internal/DistributionAdvisor.java