Javadoc
Nodes and Edges comprise an additional directed graph through the
contains-a relationship, in which a MetaParent Node contains each of its
MetaChild Nodes and Edges. An Edge may have any number of MetaParents.
EdgeMetaParentsList returns a new List of the MetaParents (in this
GraphPerspective) of the Edge in this GraphPerspective with the given
index. If there are no MetaParents then the result will be the
empty List; null is returned if no Edge at specified RootGraph index exists
in this GraphPerspective.