Authentication in dot net core preview-2.0

I tried jwt token authentication in my web api project in .net-core preview-2, but it's not working properly.

JwtBearerAppBuilderExtensions.UseJwtBearerAuthentication(IA‌​pplicationBuilder, JwtBearerOptions)' is obsolete: 'See go.microsoft.com/fwlink/?linkid=845470';

When i try same code to dot net core 1.2, it runs properly. What should i do?

i think you should use:

 var signingKey = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(Configuration.GetSection("TokenAuthentication:SecretKey").Value));


        var tokenValidationParameters = new TokenValidationParameters
        {
            // The signing key must match!
            ValidateIssuerSigningKey = true,
            IssuerSigningKey = signingKey,
            // Validate the JWT Issuer (iss) claim
            ValidateIssuer = true,
            ValidIssuer = Configuration.GetSection("TokenAuthentication:Issuer").Value,
            // Validate the JWT Audience (aud) claim
            ValidateAudience = true,
            ValidAudience = Configuration.GetSection("TokenAuthentication:Audience").Value,
            // Validate the token expiry
            ValidateLifetime = true,
            // If you want to allow a certain amount of clock drift, set that here:
            ClockSkew = TimeSpan.Zero
        };
        services.AddJwtBearerAuthentication(options =>
        {
            options.TokenValidationParameters = tokenValidationParameters;
        });
        services.AddAuthorization(options =>
        {
            options.DefaultPolicy = new AuthorizationPolicyBuilder(JwtBearerDefaults.AuthenticationScheme).RequireAuthenticatedUser().Build();
        });
        services.AddCors(options =>
        {
            options.AddPolicy("CorsPolicy",
                builder => builder.AllowAnyOrigin()
                .AllowAnyMethod()
                .AllowAnyHeader()
                .AllowCredentials());
        });