title: Value cannot be null. Parameter name: connectionString appsettings.json in starter
body: <p>I am trying to write my connection string in my appsettings.json file and bring it into my startup file but I keep getting a Value cannot be null.
  Parameter name: connectionString.  I have been using various examples but can't seem to see this new setup with ASP.NET 1.0 Core startup class.  </p>
  
  <p>Appsetting.json file:</p>
  
  <pre><code>{
  "Data": {
  "DefaultConnection": {
    "ConnectionString": "Data Source=server;Initial Catalog=dbase;Trusted_Connection=True;MultipleActiveResultSets=true"
  
  },
  "Logging": {
    "IncludeScopes": false,
    "LogLevel": {
      "Default": "Debug",
      "System": "Information",
      "Microsoft": "Information"
    }
  }
  }
  }
  </code></pre>
  
  <p>Method attempting
  Startup.cs</p>
  
  <pre><code>public Startup(IHostingEnvironment env)
      {
          var builder = new ConfigurationBuilder()
              .SetBasePath(env.ContentRootPath)
              .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
              .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
              .AddEnvironmentVariables();
          Configuration = builder.Build();
      }
  
   public void ConfigureServices(IServiceCollection services)
      {
          var connStr = Configuration.GetConnectionString("DefaultConnection");
          System.Console.WriteLine(connStr);
          services.AddDbContext&lt;DbContext&gt;(options =&gt; options.UseSqlServer(connStr)); //error right here -- Null value
  }
  </code></pre>