code: @Override
      boolean tryObtainPermission() {
          // Thread-safe
          if (clock.instant().isAfter(retryAfterWaitDuration)) {
              stateMachine.transitionToHalfOpenState();
              return true;
          }
          circuitBreakerMetrics.onCallNotPermitted();
          return false;
      }
docs: Returns false, if the wait duration has not elapsed.
  Returns true, if the wait duration has elapsed and transitions the state machine to HALF_OPEN state.
  
  @return false, if the wait duration has not elapsed. true, if the wait duration has elapsed.