Nullability of type of parameter 'obj' doesn't match overridden member (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'value' doesn't match implemented member 'void IList.this[int index].set' (possibly because of nullability attributes).

Nullability of reference types in type of 'event NotifyCollectionChangedEventHandler Series<TIndex, TValue>.CollectionChanged' doesn't match implicitly implemented member 'event NotifyCollectionChangedEventHandler? INotifyCollectionChanged.CollectionChanged'.

Nullability of reference types in type of parameter 'item' of 'void Series<TIndex, TValue>.Remove(object item)' doesn't match implicitly implemented member 'void IList.Remove(object? value)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'item' of 'void Series<TIndex, TValue>.Insert(int index, object item)' doesn't match implicitly implemented member 'void IList.Insert(int index, object? value)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'item' of 'int Series<TIndex, TValue>.IndexOf(object item)' doesn't match implicitly implemented member 'int IList.IndexOf(object? value)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'item' of 'bool Series<TIndex, TValue>.Contains(object item)' doesn't match implicitly implemented member 'bool IList.Contains(object? value)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'item' of 'int Series<TIndex, TValue>.Add(object item)' doesn't match implicitly implemented member 'int IList.Add(object? value)' (possibly because of nullability attributes).

Nullability of reference types in type of 'event NotifyCollectionChangedEventHandler UncertainOrderedPairedData.CollectionChanged' doesn't match implicitly implemented member 'event NotifyCollectionChangedEventHandler? INotifyCollectionChanged.CollectionChanged'.

Nullability of type of parameter 'obj' doesn't match overridden member (possibly because of nullability attributes).

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.