code: public static Batch batchOfKeys( final Iterator<NodeKey> keys,
                                       final long nodeCount,
                                       final float score,
                                       final String workspaceName,
                                       final RepositoryCache repository ) {
          assert nodeCount >= -1;
          if (keys == null) return emptyBatch(workspaceName, 1);
          final NodeCache cache = repository.getWorkspaceCache(workspaceName);
          return batchOfKeys(keys, nodeCount, score, workspaceName, cache);
      }
docs: Create a batch of nodes around the supplied iterator. Note that the supplied iterator is accessed lazily only when the
  batch is {@link Batch#nextRow() used}.
  
  @param keys the iterator over the keys of the nodes to be returned; if null, an {@link #emptySequence empty instance} is
  returned
  @param nodeCount the number of nodes in the iterator; must be -1 if not known, 0 if known to be empty, or a positive number
  if the number of nodes is known
  @param score the score to return for all of the nodes
  @param workspaceName the name of the workspace in which all of the nodes exist
  @param repository the repository cache used to access the workspaces and cached nodes; may be null only if the key sequence
  is null or empty
  @return the batch of nodes; never null