#2656 Fix for - Session is not provided by ClearChangeMasks when a ch…

…ange is notified (#2772)

It fixes #2656 by including in the SystemContext (taken as an argument to the OnMonitoredNodeChanged method) the Server session related to the current MonitoredItem that is going to be passed to the QueueValue.

Libraries/Opc.Ua.Server/Diagnostics/MonitoredNode.cs

@@ -294,13 +294,31 @@ public void OnMonitoredNodeChanged(ISystemContext context, NodeState node, NodeS
 
  if (monitoredItem.AttributeId == Attributes.Value && (changes & NodeStateChangeMasks.Value) != 0)
  {
- QueueValue(context, node, monitoredItem);
+ ServerSystemContext serverSystemContext;
+ if ((serverSystemContext = (context as ServerSystemContext)) != null)
+ {
+ ServerSystemContext context2 = serverSystemContext.Copy(new OperationContext(monitoredItem.Session, monitoredItem.DiagnosticsMasks));
+ QueueValue(context2, node, monitoredItem);
+ }
+ else
+ {
+ QueueValue(context, node, monitoredItem);
+ }
  continue;
  }
 
  if (monitoredItem.AttributeId != Attributes.Value && (changes & NodeStateChangeMasks.NonValue) != 0)
  {
- QueueValue(context, node, monitoredItem);
+ ServerSystemContext serverSystemContext2;
+ if ((serverSystemContext2 = (context as ServerSystemContext)) != null)
+ {
+ ServerSystemContext context3 = serverSystemContext2.Copy(new OperationContext(monitoredItem.Session, monitoredItem.DiagnosticsMasks));
+ QueueValue(context3, node, monitoredItem);
+ }
+ else
+ {
+ QueueValue(context, node, monitoredItem);
+ }
  continue;
  }
  }