@Override
    public Stream<ShapeMatch> matches(Model model, StartingContext context) {
        Collection<? extends Shape> startingShapes = context.getStartingShapes();
        Stream<? extends Shape> shapeStream = startingShapes == null ? model.shapes() : startingShapes.stream();
        return shapeStream.map(shape -> new ShapeMatch(shape, Collections.emptyMap()));
    }
An optimized Selector implementation that uses the provided Model directly
rather than needing to send each shape through the Selector machinery.

@see Selector#IDENTITY
smithy-model/src/main/java/software/amazon/smithy/model/selector/IdentitySelector.java