NServiceBus.Conventions.IsMessageType C# (CSharp) Method

        public bool IsMessageType(Type t)
        {
            Guard.AgainstNull(nameof(t), t);
            try
            {
                return MessagesConventionCache.ApplyConvention(t,
                    typeHandle =>
                    {
                        var type = Type.GetTypeFromHandle(typeHandle);

                        if (IsInSystemConventionList(type))
                        {
                            return true;
                        }
                        if (type.IsFromParticularAssembly())
                        {
                            return false;
                        }
                        return IsMessageTypeAction(type) ||
                               IsCommandTypeAction(type) ||
                               IsEventTypeAction(type);
                    });
            }
            catch (Exception ex)
            {
                throw new Exception("Failed to evaluate Message convention. See inner exception for details.", ex);
            }
        }

 public IEnumerable <RouteTableEntry> GenerateRoutes(Conventions conventions)
 {
     if (!conventions.IsMessageType(messageType))
     {
         throw new Exception($"Cannot configure routing for type '{messageType.FullName}' because it is not considered a message. Message types have to either implement NServiceBus.IMessage interface or match a defined message convention.");
     }
     yield return(new RouteTableEntry(messageType, route));
 }