public Map<ShapeId, Trait> getEndpointModifierTraits(ToShapeId toShapeId) {
        return endpointModifierTraits.get(toShapeId.toShapeId());
    }
Gets all endpoint modifier traits applied to a service.

@param toShapeId Service shape to query
@return Map of endpoint modifier trait ID to the trait
smithy-aws-endpoints/src/main/java/software/amazon/smithy/rulesengine/aws/traits/EndpointModifierIndex.java