The type 'TKey' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'TKey' doesn't match 'notnull' constraint.

The type 'K' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'K' doesn't match 'notnull' constraint.

Nullability of reference types in type of parameter 'x' of 'bool FNVByteComparison.Equals(byte[] x, byte[] y)' doesn't match implicitly implemented member 'bool IEqualityComparer<byte[]>.Equals(byte[]? x, byte[]? y)' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'y' of 'bool FNVByteComparison.Equals(byte[] x, byte[] y)' doesn't match implicitly implemented member 'bool IEqualityComparer<byte[]>.Equals(byte[]? x, byte[]? y)' (possibly because of nullability attributes).

Possible null reference argument for parameter 'other' in 'XDocument.XDocument(XDocument other)'.

Possible null reference argument for parameter 'values' in 'string string.Join(string? separator, IEnumerable<string?> values)'.

The type 'K' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'K' doesn't match 'notnull' constraint.

The type 'K' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'K' doesn't match 'notnull' constraint.

The type 'TKey' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'TKey' doesn't match 'notnull' constraint.