code: public final void refreshPermissions() {
          Request request = new Request(this, "me/permissions");
          request.setCallback(new Request.Callback() {
              @Override
              public void onCompleted(Response response) {
                  PermissionsPair permissionsPair = handlePermissionResponse(response);
                  if (permissionsPair != null) {
                      // Update our token with the refreshed permissions
                      synchronized (lock) {
                          tokenInfo = AccessToken.createFromTokenWithRefreshedPermissions(tokenInfo,
                                  permissionsPair.getGrantedPermissions(), permissionsPair.getDeclinedPermissions());
                          postStateChange(state, SessionState.OPENED_TOKEN_UPDATED, null);
                      }
                  }
              }
          });
          request.executeAsync();
      }
docs: <p>
  Issues a request to refresh the permissions on the session.
  </p>
  <p>
  If successful, this will update the permissions and call the app back with
  {@link SessionState#OPENED_TOKEN_UPDATED}.  The session can then be queried to see the granted and declined
  permissions.  If this fails because the user has removed the app, the session will close.
  </p>