presto-main/src/main/java/io/prestosql/operator/scalar/JsonExtract.java/JsonExtract/tryParseInt
class JsonExtract:    private static int tryParseInt(String fieldName, int defaultValue)
    {
        int index = defaultValue;
        try {
            index = Integer.parseInt(fieldName);
        }
        catch (NumberFormatException ignored) {
        }
        return index;
    }