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).

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.

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.

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 '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.