Code analysis warning when declaring an event in an interface

Question

Why is this declaration of an event in the following interface complaining in the code analyzer with a CA1009? In the implementation it does indeed seem to follow the standard conventions of event declaration.

using System;

namespace Client.Wpf.Utilities.MessageSubscription
{
    public interface ITrigger<TMessageType>
    {
        event EventHandler<TMessageType> Fire;
    }
}

CA1009 Declare event handlers correctly

Declare the second parameter of 'EventHandler' as an EventArgs, or an instance of a type that extends EventArgs, named 'e'.

ITrigger.cs 7

And the implementation:

using System;
//using GalaSoft.MvvmLight.Messaging;

namespace Client.Wpf.Utilities.MessageSubscription
{
    public class MvvmMessageTrigger<TMessageType> : ITrigger<TMessageType>
    {
        public MvvmMessageTrigger()
        {
            //Messenger.Default.Register<TMessageType>(this, InvokeSubscribers);
        }

        public event EventHandler<TMessageType> Fire;

        private void InvokeSubscribers(TMessageType messageType)
        {
            if (null != Fire)
            {
                Fire(this, messageType);
            }
        }
    }
}

Answer 1

The error is pretty self evident:

Declare the second parameter of 'EventHandler' as an EventArgs, or an instance of a type that extends EventArgs, named 'e'.

In my example above TMessageType was not inheriting from EventArgs, and thus the warning.