Argument of type 'IEnumerable<T?>' cannot be used for parameter 'first' of type 'IEnumerable<T>' in 'IEnumerable<T> Enumerable.Concat<T>(IEnumerable<T> first, IEnumerable<T> second)' due to differences in the nullability of reference types.

Argument of type 'IEnumerable<T?>' cannot be used for parameter 'first' of type 'IEnumerable<T>' in 'IEnumerable<T> Enumerable.Concat<T>(IEnumerable<T> first, IEnumerable<T> second)' due to differences in the nullability of reference types.

Argument of type 'IEnumerable<T?>' cannot be used for parameter 'first' of type 'IEnumerable<T>' in 'IEnumerable<T> Enumerable.Concat<T>(IEnumerable<T> first, IEnumerable<T> second)' due to differences in the nullability of reference types.

Argument of type 'IEnumerable<T?>' cannot be used for parameter 'first' of type 'IEnumerable<T>' in 'IEnumerable<T> Enumerable.Concat<T>(IEnumerable<T> first, IEnumerable<T> second)' due to differences in the nullability of reference types.

Argument of type 'IEnumerable<T?>' cannot be used for parameter 'first' of type 'IEnumerable<T>' in 'IEnumerable<T> Enumerable.Concat<T>(IEnumerable<T> first, IEnumerable<T> second)' due to differences in the nullability of reference types.

The type 'ContactInformation' defines init-only properties, deserialization of which is currently not supported in source generation mode.

The type 'PhysicalDescription' defines init-only properties, deserialization of which is currently not supported in source generation mode.

The type 'FamilyInfo' defines init-only properties, deserialization of which is currently not supported in source generation mode.

The type 'Person' defines init-only properties, deserialization of which is currently not supported in source generation mode.