code: public final void closeAndClearTokenInformation() {
          if (this.tokenCachingStrategy != null) {
              this.tokenCachingStrategy.clear();
          }
          Utility.clearFacebookCookies(staticContext);
          Utility.clearCaches(staticContext);
          close();
      }
docs: Closes the local in-memory Session object and clears any persisted token
  cache related to the Session.