namespace ServiceStack.Common.Web
{
    public static class HttpHeaders
    {
        public const string XParamOverridePrefix = "X-Param-Override-";

        public const string XHttpMethodOverride = "X-Http-Method-Override";

        public const string XUserAuthId = "X-UAId";

        public const string XForwardedFor = "X-Forwarded-For";

        public const string XRealIp = "X-Real-IP";

        public const string Referer = "Referer";

        public const string CacheControl = "Cache-Control";

        public const string IfModifiedSince = "If-Modified-Since";

        public const string LastModified = "Last-Modified";

        public const string Accept = "Accept";

        public const string AcceptEncoding = "Accept-Encoding";

        public const string ContentType = "Content-Type";

        public const string ContentEncoding = "Content-Encoding";

        public const string ContentLength = "Content-Length";

        public const string ContentDisposition = "Content-Disposition";

        public const string Location = "Location";

        public const string SetCookie = "Set-Cookie";

        public const string ETag = "ETag";

        public const string Authorization = "Authorization";

        public const string WwwAuthenticate = "WWW-Authenticate";

        public const string AllowOrigin = "Access-Control-Allow-Origin";

        public const string AllowMethods = "Access-Control-Allow-Methods";

        public const string AllowHeaders = "Access-Control-Allow-Headers";
        
        public const string AllowCredentials = "Access-Control-Allow-Credentials";
    }
}
namespace ServiceStack.Common.Web
{
    public static class HttpHeaders
    {
        public const string XParamOverridePrefix = "X-Param-Override-";

        public const string XHttpMethodOverride = "X-Http-Method-Override";

        public const string XUserAuthId = "X-UAId";

        public const string XForwardedFor = "X-Forwarded-For";

        public const string XRealIp = "X-Real-IP";

        public const string Referer = "Referer";

        public const string CacheControl = "Cache-Control";

        public const string IfModifiedSince = "If-Modified-Since";

        public const string IfNoneMatch = "If-None-Match";

        public const string LastModified = "Last-Modified";

        public const string Accept = "Accept";

        public const string AcceptEncoding = "Accept-Encoding";

        public const string ContentType = "Content-Type";

        public const string ContentEncoding = "Content-Encoding";

        public const string ContentLength = "Content-Length";

        public const string ContentDisposition = "Content-Disposition";

        public const string Location = "Location";

        public const string SetCookie = "Set-Cookie";

        public const string ETag = "ETag";

        public const string Authorization = "Authorization";

        public const string WwwAuthenticate = "WWW-Authenticate";

        public const string AllowOrigin = "Access-Control-Allow-Origin";

        public const string AllowMethods = "Access-Control-Allow-Methods";

        public const string AllowHeaders = "Access-Control-Allow-Headers";
        
        public const string AllowCredentials = "Access-Control-Allow-Credentials";
    }
}
Add a const string field for the If-None-Match HTTP header
Add a const string field for the If-None-Match HTTP header
