title: Flutter: avoid build() method of previous route being called when navigate to next route
body: <p>My flutter app is showing a splash screen (<code>statefulWidget</code>) as a first route. This route is showing an animation while, on the background, calling an API to get some data.</p>
  
  <p>Once the data has been received and the animation is complete, it navigates to the second route.</p>
  
  <p>All works fine, except that, when calling the <code>Navigator</code> to navigate to the second route, the second route is shown, but i can see again the response from the API on the first route, that is being called.</p>
  
  <p>It turns out that, when the second route is built, the build method of the previous route is called too, making an unnecessary API call again.</p>
  
  <p>How to avoid this behaviour?, I believe this must be a bug on <code>Flutter</code>??</p>
  
  <p><strong>current flow (non-desired): SplashRoute(build) ---> Navigator ---> HomeRoute(build)+SplashRoute(build)</strong></p>
  
  <p><strong>desired flow: SplashRoute(build) ---> Navigator ---> HomeRoute(build)</strong></p>