@Override
          public IterationMode next(final NodeType node) {
            toSelect.addAll(GraphAlgorithms.collectParents(node, deselectedFilter));

            return IterationMode.CONTINUE;
          }
Expands the current selection up. This means that all parents of the currently selected nodes
are selected too.

@param <NodeType> Type of the nodes in the graph.
@param graph The graph in question.
java/zylib/src/main/java/com/google/security/zynamics/zylib/gui/zygraph/helpers/GraphHelpers.java