如何在Ocelot的PreAuthenticationMiddleware中停止请求？

public class PreAuthenticationMiddleware
{
    private readonly RequestDelegate _next;

    public PreAuthenticationMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task Invoke(HttpContext context)
    {
        try
        {
            // 执行一些前置认证操作

            if (需要停止请求的条件)
            {
                throw new StopRequestException("请求被中止"); // 抛出异常停止请求
            }

            await _next(context); // 继续请求流程
        }
        catch (StopRequestException ex)
        {
            // 处理异常并返回给客户端
            context.Response.StatusCode = 400;
            await context.Response.WriteAsync(ex.Message);
        }
    }
}