An example claim validation rule expression that matches the validation automatically
  applied when username.claim is set to 'email' is 'claims.?email_verified.orValue(true) == true'. 
  By explicitly comparing the value to true, we let type-checking see the result will be a boolean, 

   * acquire other locks, risking deadlocks.
   */
  @CanIgnoreReturnValue
  @Override
  public boolean cancel(boolean mayInterruptIfRunning) {
    @RetainedLocalRef Object localValue = value();
    boolean rValue = false;
    if (localValue == null | localValue instanceof DelegatingToFuture) {
      // Try to delay allocating the exception. At this point we may still lose the CAS, but it is
      // certainly less likely.