@Override
 @SuppressWarnings(value = {"unchecked"})
 public void accept(SRC key, V value) {
   PVector<V> newv = buffer.swap((old) -> old.plus(value));
   if (emit.test(newv)) {
     PVector<V> downstreamValue = buffer.swapReturnOld((old) -> TreePVector.empty());
     firehose.notify(destination, downstreamValue);
   }
 }
      @SuppressWarnings("ReturnOfCollectionOrArrayField")
      @Override
      protected final PVector<T> computeNext() {

        if (nextPageURI == null) {
          return endOfData();
        }
        TypedResponseWithEntity<List<T>> response =
            EvrythngApiBuilder.get(apiKey, nextPageURI, responseStatus, pageType)
                .executeWithResponse();
        nextPageURI = nextPageURI(response);
        return response.entity() != null
            ? TreePVector.from(response.entity())
            : TreePVector.<T>empty();
      }