Possible multiple enumerations of 'IEnumerable' collection. Consider using an implementation that avoids multiple enumerations. (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1851)

Prefer 'static readonly' fields over constant array arguments if the called method is called repeatedly and is not mutating the passed array (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1861)

Prefer using 'string.Equals(string, StringComparison)' to perform a case-insensitive comparison, but keep in mind that this might cause subtle changes in behavior, so make sure to conduct thorough testing after applying the suggestion, or if culturally sensitive comparison is not required, consider using 'StringComparison.OrdinalIgnoreCase' (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1862)

Prefer the string comparison method overload of 'string.Contains(string)' that takes a 'StringComparison' enum value to perform a case-insensitive comparison, but keep in mind that this might cause subtle changes in behavior, so make sure to conduct thorough testing after applying the suggestion, or if culturally sensitive comparison is not required, consider using 'StringComparison.OrdinalIgnoreCase' (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1862)

In method 'Lookup', replace the call to 'ToLower' with 'ToUpperInvariant' (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1308)

In method 'Lookup', replace the call to 'ToLower' with 'ToUpperInvariant' (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1308)

In method 'Lookup', replace the call to 'ToLower' with 'ToUpperInvariant' (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1308)

Possible multiple enumerations of 'IEnumerable' collection. Consider using an implementation that avoids multiple enumerations. (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1851)

Possible multiple enumerations of 'IEnumerable' collection. Consider using an implementation that avoids multiple enumerations. (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1851)