NodeId.Null identifier not "0" after deserializing ExtensionObjects from JSON

[pzatschl]

Type of issue

• Bug
• Enhancement
• Compliance
• Question
• Help wanted

Current Behavior

When trying to deserialize ExtensionObjects from JSON an error occurs that overwrites the NodeId.Null field. We suspect this is due to the NodeId.Null being handed out as a reference and then being modified.

The below Code runs fine for one iteration in a loop, but will hang when entered again.

var text1 = "[{\"Body\":{\"KeyValuePair\":{\"@xmlns\":\"http://opcfoundation.org/UA/2008/02/Types.xsd\"," +
    "\"Key\":{\"Name\":\"o\",\"NamespaceIndex\":\"0\"},\"Value\":{\"Value\":" +
    "{\"ListOfExtensionObject\":{\"ExtensionObject\":[" +
    "{\"Body\":{\"KeyValuePair\":{\"Key\":{\"Name\":\"stringProp\",\"NamespaceIndex\":\"0\"},\"Value\":{\"Value\":" +
    "{\"String\":\"EinString\"}}}},\"TypeId\":{\"Identifier\":\"i=14801\"}},{\"Body\":{\"KeyValuePair\":{\"Key\":" +
    "{\"Name\":\"intProp\",\"NamespaceIndex\":\"0\"},\"Value\":{\"Value\":{\"Int32\":\"1\"}}}},\"TypeId\":" +
    "{\"Identifier\":\"i=14802\"}}]}}}}},\"TypeId\":" +
    "{\"Identifier\":\"i=14803\"}}]";

JsonConvert.DeserializeObject<ExtensionObject[]>(text1);

Attaching a debugger reveals the following:

a SSCCE (Short, Self-Contained, Correct Example) is attached
OPC_ConsoleServer.zip

Expected Behavior

NodeId.Null Identifier should not be able to be modified

Steps To Reproduce

1. Start Server
2. Deserialize from JSON

"[{\"Body\":{\"KeyValuePair\":{\"@xmlns\":\"http://opcfoundation.org/UA/2008/02/Types.xsd\"," +
                    "\"Key\":{\"Name\":\"o\",\"NamespaceIndex\":\"0\"},\"Value\":{\"Value\":" +
                    "{\"ListOfExtensionObject\":{\"ExtensionObject\":[" +
                    "{\"Body\":{\"KeyValuePair\":{\"Key\":{\"Name\":\"stringProp\",\"NamespaceIndex\":\"0\"},\"Value\":{\"Value\":" +
                    "{\"String\":\"EinString\"}}}},\"TypeId\":{\"Identifier\":\"i=14801\"}},{\"Body\":{\"KeyValuePair\":{\"Key\":" +
                    "{\"Name\":\"intProp\",\"NamespaceIndex\":\"0\"},\"Value\":{\"Value\":{\"Int32\":\"1\"}}}},\"TypeId\":" +
                    "{\"Identifier\":\"i=14802\"}}]}}}}},\"TypeId\":" +
                    "{\"Identifier\":\"i=14803\"}}]"

4. Stop Server
5. Deserialize from JSON (s. above)
6. Application hangssee attached code:
   OPC_ConsoleServer.zip

Environment

- OS: Windows 11, Windows Server
- Environment: Visual Studio 2022 17.12.4
- Runtime: .NET Standard (e.g. .NET 8)
- Nuget Version: 1.5.374.126
- Component: Opc.Ua.Core
- Server: n/a
- Client: n/a

Anything else?

Example Project:
OPC_ConsoleServer.zip

[mregen]

great find, NodeId should really be immutable