public Set<ShapeId> getAppliedTraits() {
        return Collections.unmodifiableSet(getTraitCache().traitIdsToShapes.keySet());
    }
Gets a set of every trait shape ID that is used in the model.

@return Returns the shape IDs of traits used in the model.
smithy-model/src/main/java/software/amazon/smithy/model/Model.java