Immutable built in types and code generation

[marcschier]

Change built in types to readonly structs
Update localized text implementation to use JSON text serializer
Status code with symbolic names
Immutable node ids - no boxing for int identifiers (in nodeId struct)
No boxing for all built in types <= 8 bytes in Variant.
Split user identity token and token handling via token handler Add migration guide for breaking changes

Proposed changes

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Related Issues

• Fixes
  <Performance Issue>: IsNullTypeId  #3533
  Fix complex type system test case LoadAllServerDataTypeSystemsAsync(i=92) #3477
  Breaking changes migration guide #3425
  Getting NodeState for i=68 (PropertyType) returns an object of type BaseDataVariableTypeState #2969
  Change implementation of built in types and code generation to generate efficient code leveraging it. #3537

Types of changes

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• Bugfix (non-breaking change which fixes an issue)
• Enhancement (non-breaking change which adds functionality)
• Test enhancement (non-breaking change to increase test coverage)
• Breaking change (fix or feature that would cause existing functionality to not work as expected, requires version increase of Nuget packages)
• Documentation Update (if none of the other choices apply)

Checklist

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• I have signed the CLA.
• I ran tests locally with my changes, all passed.
• I fixed all failing tests in the CI pipelines.
• I fixed all introduced issues with CodeQL and LGTM.
• I have added tests that prove my fix is effective or that my feature works and increased code coverage.
• I have added necessary documentation (if appropriate).
• Any dependent changes have been merged and published in downstream modules.

Further comments

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[romanett]

Is IsAbsolute true or false for NullNodeId?

[marcschier]

IsNull => !IsAbsolute && m_nodeId.IsNull; So above is ok, but below could remove the IsNull check

[romanett]

Here null is checked first and then IsAbsolute

[marcschier]

Will remove in my next PR.

[romanett]

return IUserIdenntityTokenHandler?

[marcschier]

We could, but since it just provides access to the token (without state) it should be ok to just return the token for use later. The state is in the token handler and it has Dispose semantics, and we can keep these very close to the code that uses them (via using).

[romanett]

Why is the StatusCodes.Bad needed?

[marcschier]

It is the default if the variant is not a status code. Maybe BadTypeMismatch could make more sense here, but then again, the type mismatch is because the variant has no status code, so I personally like generic Bad here.

[romanett]

Is this covered in the migration guide?

[marcschier]

No, because it should not make any difference to callers because these "reflection" lookups are now generated.