@Override
    public List<ValidationEvent> validate(Model model) {
        ServiceIndex serviceIndex = ServiceIndex.of(model);
        return model.shapes(ServiceShape.class)
                .flatMap(service -> validateService(service, serviceIndex).stream())
                .collect(Collectors.toList());
    }
Ensures that every entry in {@code eventStreamHttp} also appears in
the {@code http} property of a protocol trait.
smithy-aws-traits/src/main/java/software/amazon/smithy/aws/traits/protocols/ProtocolHttpValidator.java