protected GraphTraversal searchVerticesPropertyConstraints(GraphTraversal t, final Map search) {
        for (final Map.Entry e : ((Map<?,?>) search).entrySet()) {
            final Object k = e.getKey();
            if (!(k instanceof String)) continue;
            t = t.has((String) k, e.getValue());
        }
        return t;
    }
Translate the Map into a g.V() traversal against the supplied graph. Graph providers will presumably optimize
this traversal to use whatever indices are present and appropriate for efficiency.

Callers are responsible for closing this iterator when finished.
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/MergeElementStep.java