title: how to get a custom attribute in a user pool using aws-android-sdk
body: <p>I can connect to aws user pool using aws-android-sdk. I can get standard attributes such as e-mail, given name etc... but IMPOSSIBLE to get a custom attribute.
  Here is the function used:</p>
  
  <pre><code>GetDetailsHandler detailsHandler = new GetDetailsHandler() {
          @Override
          public void onSuccess(CognitoUserDetails cognitoUserDetails) {
              // Extract user details
          }
  
          @Override
          public void onFailure(Exception exception) {
          }
      };
  </code></pre>