private boolean probe(File modelFile) {
        try (JsonParser parser = Jackson.mapper().createParser(modelFile)) {
            while (parser.nextToken() != null) {
                JsonToken token = parser.currentToken();
                if (token == JsonToken.FIELD_NAME) {
                    if ("tree_info".equals(parser.currentName())) return true;
                }
            }
            return false;
        } catch (IOException e) {
            throw new IllegalArgumentException("Could not read '" + modelFile + "'", e);
        }
    }
Returns true if the give file looks like a LightGBM json file.
Currently, we just check if the json has an element called "tree_info"
model-integration/src/main/java/ai/vespa/rankingexpression/importer/lightgbm/LightGBMImporter.java