Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Nullability of reference types in return type of 'Task<TResult?> CustomeDiagnosticsProvider.ExecuteActivityAsync<TResult>(CreateActivityInfo createActivityInfo, Func<Activity?, CancellationToken, Task<TResult>> action, CancellationToken cancellationToken = default(CancellationToken))' doesn't match implicitly implemented member 'Task<TResult> IDiagnosticsProvider.ExecuteActivityAsync<TResult>(CreateActivityInfo createActivityInfo, Func<Activity?, CancellationToken, Task<TResult>> action, CancellationToken cancellationToken = default(CancellationToken))'.

Cannot convert null literal to non-nullable reference type.

'TestBase<TEntryPoint, TWContext, TRContext>.Fixture' hides inherited member 'TestFixtureCore<TEntryPoint>.Fixture'. Use the new keyword if hiding was intended.

Cannot convert null literal to non-nullable reference type.

'TestWriteBase<TEntryPoint, TWContext>.Fixture' hides inherited member 'TestFixtureCore<TEntryPoint>.Fixture'. Use the new keyword if hiding was intended.

Cannot convert null literal to non-nullable reference type.

'TestReadBase<TEntryPoint, TRContext>.Fixture' hides inherited member 'TestFixtureCore<TEntryPoint>.Fixture'. Use the new keyword if hiding was intended.