title: Newtonsoft deserialization adds nulls to list
body: <p>I'm simply trying deserialize some JSON from a file into a list of objects, using the Newtonsoft JSON library in C#. Here are the contents of the <em>MeetingFile.txt</em> file:</p>
  
  <pre><code>[
    {
      "People": [
        {
          "FirstName": "Malcolm",
          "LastName": "Reynolds"
        },
        {
          "FirstName": "Hoban",
          "LastName": "Washburne"
        }
      ],
      "PairDate": "1/14/2016"
    }
  ]
  </code></pre>
  
  <p>And here's the code for deserializing the object graph:</p>
  
  <pre><code>using (var streamReader = new StreamReader(@"C:\Temp\MeetingFile.txt"))
  {
      var fileContents = streamReader.ReadToEnd();
      var meetingHistory = JsonConvert.DeserializeObject&lt;List&lt;PairHistoryItem&gt;&gt;(fileContents);
      var serialized = JsonConvert.SerializeObject(meetingHistory);
      return meetingHistory;
  }
  </code></pre>
  
  <p>And the classes:</p>
  
  <pre><code>public class Person
  {
      public readonly string FirstName;
      public readonly string LastName;
      public string FullName =&gt; $"{FirstName} {LastName}";
  
      public List&lt;IPairHistoryItem&gt; PairHistory;
  
      public Person(string firstName, string lastName)
      {
          FirstName = firstName;
          LastName = lastName;
      }
  }
  
  public class PairHistoryItem
  {
      public List&lt;Person&gt; People { get; }
      public DateTime PairDate { get; }
  
      public PairHistoryItem(Person person1, Person person2, DateTime pairDate)
      {
          People = new List&lt;Person&gt; {person1, person2};
          PairDate = pairDate;
      }
  }
  </code></pre>
  
  <p>But for whatever reason, this is what's contained in the <strong><em>serialized</em></strong> variable in my deserialization code:</p>
  
  <pre><code>[
    {
      "People": [
        null,
        null,
        {
          "FirstName": "Malcolm",
          "LastName": "Reynolds",
          "PairHistory": null,
          "FullName": "Malcolm Reynolds"
        },
        {
          "FirstName": "Hoban",
          "LastName": "Washburne",
          "PairHistory": null,
          "FullName": "Hoban Washburne"
        }
      ],
      "PairDate": "2016-01-14T00:00:00"
    }
  ]
  </code></pre>
  
  <p>Where do the nulls at the beginning of the list come from? As far as I can tell, the JSON in my file is formatted properly. Am I missing some setting for the JSON Converter?</p>