title: Apollo boost - __typename in query prevent new mutation
body: <p>I have a problem in my meteor/react/apollo (with boost) project. When I query data from the server, it adds __typename to every object and subobject in my query but it my case it creates a major issue as I normally reuse these data to send them to other mutation. Now the other mutation tell me there is an error because the __typename field is not defined in my graphql schema.</p>
  
  <p>I tried to fix by adding the addTypename: false field to my apollo client but it didn't change anything (note I am using apollo boost, that may be why it is not sworking) :</p>
  
  <pre><code>const client = new ApolloClient({
      uri: Meteor.absoluteUrl('graphql'),
      addTypename: false,
      request: operation =&gt;
          operation.setContext(() =&gt; ({
              headers: {
                  authorization: Accounts._storedLoginToken()
              }
          }))
  })
  </code></pre>
  
  <p>Also it seems than even if it worked it is not very optimized. It seems to me very problematic that a field is added to the query results and I am surprised not to find any clear solution online. Some proposed solution where :</p>
  
  <ul>
  <li>filter manually on client side</li>
  <li>add middleware to apollo</li>
  <li>add the __typename field to all my schemas...</li>
  </ul>
  
  <p>but none of them seem to fit the 'simplcity' apollo is suppose to bring for queries. I hope there is a simpler, more logical solution provided, but so far, could not find any.</p>