code: boolean requestAccounts(Callback callback) {
          boolean isSuccessful = false;
  
          Session session = Session.getActiveSession();
          if (session != null && session.isOpened()) {
              // Construct fields to request.
              Bundle params = new Bundle();
              params.putString(ACCOUNTS_LISTING_FEILDS_KEY, ACCOUNTS_LISTING_FIELDS_VALUE);
  
              // Construct and execute albums listing request.
              Request request = new Request(session, ACCOUNTS_LISTING_GRAPH_PATH, params, HttpMethod.GET, callback);
              request.executeAsync();
  
              isSuccessful = true;
          }
          return isSuccessful;
      }
docs: Asynchronously requests the Page accounts associated with the linked account. Requires an opened active {@link Session}.
  
  @param callback a {@link Callback} when the request completes.
  @return true if the request is made; false if no opened {@link Session} is active.