Possible null reference argument for parameter 'source' in 'IEnumerable<object> Enumerable.Cast<object>(IEnumerable source)'.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Possible null reference argument for parameter 'source' in 'IEnumerable<object> Enumerable.Cast<object>(IEnumerable source)'.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

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

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

Theory method 'From_IEnumerable' on test class 'IReadOnlyListTestSuite' does not use parameter '__'. Use the parameter, or remove the parameter and associated data. (https://xunit.net/xunit.analyzers/rules/xUnit1026)