fix(code-samples): visible non-constant fields

[brokenthorn]

Non-constant fields should not be visible.

Summary

Proposes a fix in accordance with .NET code analysis usage rule: https://docs.microsoft.com/en-us/dotnet/fundamentals/code-analysis/quality-rules/ca2211

Cause

A public or protected static field is not constant nor is it read-only.

Rule description

Static fields that are neither constants nor read-only are not thread-safe. Access to such a field must be carefully controlled and requires advanced programming techniques for synchronizing access to the class object. Because these are difficult skills to learn and master, and testing such an object poses its own challenges, static fields are best used to store data that does not change. This rule applies to libraries; applications should not expose any fields.

[IEvangelist]

Looks good to me, we'll - thank you 🙏

[adegeo]

@IEvangelist I think we need to be more cautious when accepting PRs into the architecture guidelines. This change broke the GetAll method in the base class as it doesn't return the members anymore since they were converted from fields to properties. Also, the sample project is out of date now: https://github.com/dotnet-architecture/eShopOnContainers/blob/dev/src/Services/Ordering/Ordering.Domain/AggregatesModel/BuyerAggregate/CardType.cs

[IEvangelist]

@IEvangelist David Pine FTE I think we need to be more cautious when accepting PRs into the architecture guidelines. This change broke the GetAll method in the base class as it doesn't return the members anymore since they were converted from fields to properties. Also, the sample project is out of date now: https://github.com/dotnet-architecture/eShopOnContainers/blob/dev/src/Services/Ordering/Ordering.Domain/AggregatesModel/BuyerAggregate/CardType.cs

@adegeo That's a good call out, in hind site that is a breaking change. When I reviewed I did look around at its usage and it seemed accurate at the time. See #24236