import com.google.common.base.Optional;
import com.google.common.collect.ForwardingObject;
import com.google.common.util.concurrent.CheckedFuture;
import javax.annotation.Nonnull;
import com.google.common.base.Optional;
import com.google.common.collect.ForwardingObject;
import com.google.common.util.concurrent.CheckedFuture;
import javax.annotation.Nonnull;