Optional
Adjacency accessor for adjacency-dependent rules. Optional: a graph without it treats adjacency rules as having no neighbor fan-out (and the engine emits STYLE_ADJACENCY_WITHOUT_NEIGHBORS once if such a rule exists).
Adjacency accessor for adjacency-dependent rules. Optional: a graph without it treats adjacency rules as having no neighbor fan-out (and the engine emits STYLE_ADJACENCY_WITHOUT_NEIGHBORS once if such a rule exists).