MediatorInterfaces.cs

public interface IPreRequestHandler<in TRequest>
    {
        void Handle(TRequest request);
    }

    public interface IAsyncPreRequestHandler<in TRequest>
    {
        Task Handle(TRequest request);
    }

    public interface IPostRequestHandler<in TRequest, in TResponse>
    {
        void Handle(TRequest request, TResponse response);
    }

    public interface IAsyncPostRequestHandler<in TRequest, in TResponse>
    {
        Task Handle(TRequest reqeust, TResponse response);
    }