protected override Exception PayloadWhenNull(IAttributeAccessor context)
{
var message = (IMessage)context.GetAttribute(ErrorMessageUtils.FAILED_MESSAGE_CONTEXT_KEY);
var description = "No retry exception available; " +
"this can occur, for example, if the RetryPolicy allowed zero attempts " +
"to execute the handler; " +
"RetryContext: " + context.ToString();
return(message == null
? new RetryExceptionNotAvailableException(description)
: new RetryExceptionNotAvailableException(message, description));
}