Change return type of method 'ToIrregularPairsCore' from 'System.Collections.Generic.IReadOnlyCollection<(System.DateTime Date, CompanyCalendar.HolidayKind IrregularKind)>' to 'System.Collections.ObjectModel.ReadOnlyCollection<(System.DateTime Date, CompanyCalendar.HolidayKind Value)>' for improved performance (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1859)

Change type of parameter 'csv' from 'CsvHelper.IReader' to 'CsvHelper.CsvReader' for improved performance (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1859)

Type 'HolidayItemRecord' 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)

Dereference of a possibly null reference.

'RelationalEntityTypeBuilderExtensions.HasComment<TEntity>(EntityTypeBuilder<TEntity>, string?)' is obsolete: 'Configure this using ToTable(t => t.HasComment()) instead.'

'EventsResource.ListRequest.TimeMin' is obsolete: 'This property is obsolete and may behave unexpectedly; please use TimeMinDateTimeOffset instead.'

'EventsResource.ListRequest.TimeMax' is obsolete: 'This property is obsolete and may behave unexpectedly; please use TimeMaxDateTimeOffset instead.'

'EventDateTime.DateTime' is obsolete: 'This property is obsolete and may behave unexpectedly; please use DateTimeDateTimeOffset instead.'

'EventDateTime.DateTime' is obsolete: 'This property is obsolete and may behave unexpectedly; please use DateTimeDateTimeOffset instead.'