Possible null reference argument for parameter 'item' in 'void List<object>.Add(object item)'.

Type 'TestClass' can be sealed because it has no subtypes in its containing assembly and is not externally visible (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1852)

Member 'SlowMethod2' does not access instance data and can be marked as static (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1822)

Member 'SlowMethod3' does not access instance data and can be marked as static (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1822)

Public method 'Dispose' on test class 'SettingsTest' should be marked as a Fact. Reduce the visibility of the method, or add a Fact attribute to the method. (https://xunit.net/xunit.analyzers/rules/xUnit1013)

Avoid multiple blank lines (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/style-rules/ide2000)

Dereference of a possibly null reference.

Possible null reference return.

Avoid multiple blank lines (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/style-rules/ide2000)