private Optional<String> modelChanged(OnnxModelCost.ModelInfo a, OnnxModelCost.ModelInfo b) {
        log.log(FINE, "Checking if model has changed (%s) -> (%s)".formatted(a, b));
        if (a.estimatedCost() != b.estimatedCost()) return Optional.of("estimated cost");
        if (a.hash() != b.hash()) return Optional.of("model hash");
        if (! a.onnxModelOptions().equals(b.onnxModelOptions())) return Optional.of("model option(s)");
        return Optional.empty();
    }
If Onnx models change in a way that requires restart of containers in
a container cluster this validator will make sure that restartOnDeploy is set for
configs for this cluster.

@author hmusum
config-model/src/main/java/com/yahoo/vespa/model/application/validation/change/RestartOnDeployForOnnxModelChangesValidator.java