code: @NotNull
    protected CompletableFuture<R> enqueue(@NotNull final Meta meta, @NotNull final T context) {
      State<T, R> state = objectQueue.get(meta.getOid());
      if (state != null) {
        if (state.future.isCancelled()) {
          objectQueue.remove(meta.getOid(), state);
          state = null;
        }
      }
      if (state == null) {
        final State<T, R> newState = new State<>(meta, context);
        state = objectQueue.putIfAbsent(meta.getOid(), newState);
        if (state == null) {
          state = newState;
          stateEnqueue(true);
        }
      }
      return state.future;
    }
docs: This method start send object metadata to server.
  
  @param context Object worker context.
  @param meta    Object metadata.
  @return Return future with result. For same objects can return same future.