presto-main/src/main/java/io/prestosql/util/JsonUtil.java/JsonUtil/currentTokenAsLongDecimal
class JsonUtil:    public static Slice currentTokenAsLongDecimal(JsonParser parser, int precision, int scale)
            throws IOException
    {
        BigDecimal bigDecimal = currentTokenAsJavaDecimal(parser, precision, scale);
        if (bigDecimal == null) {
            return null;
        }
        return encodeUnscaledValue(bigDecimal.unscaledValue());
    }