-import com.google.common.base.MoreObjects;
-import com.google.common.base.Optional;
-import com.google.common.base.Preconditions;
-import com.google.common.base.Strings;
-import com.google.common.collect.Lists;
-import com.google.common.util.concurrent.CheckedFuture;
-import com.google.common.util.concurrent.Futures;
+import static com.google.common.base.Preconditions.checkArgument;
+import static java.util.Objects.requireNonNull;
+import static org.opendaylight.yangtools.util.concurrent.FluentFutures.immediateFailedFluentFuture;
+import static org.opendaylight.yangtools.util.concurrent.FluentFutures.immediateFluentFuture;
+
+import com.google.common.base.MoreObjects.ToStringHelper;
+import com.google.common.util.concurrent.FluentFuture;
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;