-import com.google.common.base.Objects;
-import com.google.common.base.Objects.ToStringHelper;
-import com.google.common.base.Preconditions;
-import com.google.common.util.concurrent.CheckedFuture;
+import static java.util.Objects.requireNonNull;
+
+import com.google.common.base.MoreObjects;
+import com.google.common.base.MoreObjects.ToStringHelper;