OptionalassertedOptionalconfidenceOptionalkeyA stable edge id supplied by the host (issue #31). Omitted, the
graph generates one, and a host that rebuilds its UGM from its
own data gets a different id for the same edge on every rebuild,
which breaks anything keyed by edge id (selection, overlays, a
selected edge in the URL) across rebuilds. The key must be
unique across ALL edges of the graph, not just between one pair
of nodes; addEdge throws on a duplicate.
OptionalpropertiesOptionalprovenance_Optionaltemporal_Optionaltemporal_
Input for adding an edge.