title: Mongodb not return null values in list in ktor
body: <p>I'm trying to get <code>null</code> value from <code>collection</code> but in list could not get/</p>
  <p><strong>My KTOR code</strong></p>
  <pre><code>            val teacherList = teacherTableCollection.find().toList()
          
          if (teacherList.isNotEmpty()) {
              call.respond(SuccessResponse(&quot;Teacher List&quot;, teacherList))
          } else {
              call.respond(SuccessResponse(&quot;Teacher List&quot;, &quot;Sorry, teacher not added yet.&quot;))
          }
  </code></pre>
  <p><strong>Expected Result</strong></p>
  <pre><code>{
  &quot;message&quot;: &quot;Teacher List&quot;,
  &quot;data&quot;: [
      {
          &quot;t_id&quot;: 11,
          &quot;t_name&quot;: &quot;Pratik”,
          “s_id”: null
      },
      {
          &quot;t_id&quot;: 12,
          &quot;t_name&quot;: &quot;Pratik”,
          “s_id”: null
      }
  ]}
  </code></pre>
  <p><strong>but get a response below</strong></p>
  <pre><code>{
  &quot;message&quot;: &quot;Teacher List&quot;,
  &quot;data&quot;: [
      {
          &quot;t_id&quot;: 10,
          &quot;t_name&quot;: &quot;Pratik&quot;,
          &quot;s_id&quot;: 0
      },
      {
          &quot;t_id&quot;: 11,
          &quot;t_name&quot;: &quot;Pratik&quot;
      },
      {
          &quot;t_id&quot;: 12,
          &quot;t_name&quot;: &quot;Pratik&quot;
      }
  ]}
  </code></pre>