Provide empty collection as fallback in foreach loop

[mrsuciu]

Proposed changes

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Related Issues

• Fixes CustomNodeManager2.AddReverseReferences crashes in foreach loop when m_predefinedNodes is null #2964

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[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 55.40%. Comparing base (f7815c8) to head (ff1f582).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...ies/Opc.Ua.Server/Diagnostics/CustomNodeManager.cs	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2965      +/-   ##
==========================================
- Coverage   55.40%   55.40%   -0.01%     
==========================================
  Files         352      352              
  Lines       67859    67859              
  Branches    13908    13908              
==========================================
- Hits        37598    37597       -1     
- Misses      26136    26142       +6     
+ Partials     4125     4120       -5     

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[romanett]

I find an explicit null check before the loop more readable. Please also fix dispose method of customNodeManager, this is a regression from #2915

[mregen]

another option were to initialize m_predefinedNodes in the constructor and get rid of all the null checks

[romanett]

#2966