This should support an annotation like this:

@InProperties public void setMap(Map<String, String> map);
@InProperties public Map<String, String> getMap();

setMap would replace all current values in the map with the new values.
getMap would return a read-only representation of the map.

Jess:
@InProperties("map1") ...
@InProperties("map2") ... could even handle multiple maps per model (through adjacent MapModel vertex'es label).

The difference between AdjacentMap and InVertexMap is that AdjacentMap is stored in adjacent vertex. InVertex is stored in the same vertex.

Use case: InVertex can access "this" vertex'es properties through a Map. AdjacentMap can access other vertexes

Related Frames ticket: https://github.com/tinkerpop/frames/issues/100