title: Flutter Comparing 2 lists of objects using map and contains not working
body: <p>I have 2 lists of Objects namely newList and oldList as shown below:</p>
  
  <p>newList: <code>[Object{id: -LhnrmWPWN2X_cWdIAQW, title: , category: abandoned, latitude: -17.8594103, longitude: 30.9615846}, Object{id: -LhnpMHQ3l288W28qoDW, title: , category: potholes, latitude: -17.8593472, longitude: 30.9614917}]</code></p>
  
  <p>oldList: <code>[Object{id: -LhnpMHQ3l288W28qoDW, title: , category: potholes, latitude: -17.8593472, longitude: 30.9614917}]</code></p>
  
  <p>The problem is that using contains is not working when checking if all objects in newList are in oldList using the following code:</p>
  
  <p><code>newList.where((Object p) =&gt; !oldList.contains(p))
              .map((Object obj) =&gt; print('\n\n\n\ntest \n$obj'))
              .toList();</code></p>
  
  <p>In fact this code is returning true for both instances of the object in newList.</p>
  
  <p>I expect that the code should return true for only one of the objects.</p>
  
  <p>Please assist.</p>