import static com.google.common.util.concurrent.Futures.immediateFailedFuture;
import static com.google.common.util.concurrent.Futures.immediateFuture;
import static com.google.common.util.concurrent.FuturesGetChecked.checkExceptionClassValidity;
import static com.google.common.util.concurrent.FuturesGetChecked.getChecked;
import static com.google.common.util.concurrent.FuturesGetChecked.isCheckedException;

          if (exceptionClass.equals(knownGood.get())) {
            return;
          }
          // TODO(cpovirk): if reference has been cleared, remove it?
        }
        checkExceptionClassValidity(exceptionClass);

        /*
         * It's very unlikely that any loaded Futures class will see getChecked called with more