private void configurePredicates(final P<Object> predicate) {
        if (predicate instanceof ConnectiveP)
            ((ConnectiveP<Object>) predicate).getPredicates().forEach(this::configurePredicates);
        else {
            final String selectKey = getSelectKey(predicate);
            this.selectKeys.add(selectKey);
            this.scopeKeys.add(selectKey);
        }
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/filter/WherePredicateStep.java