public static Long toLong(Object value) {
        if (value == null || value instanceof Long) {
            return (Long) value;
        }

        if (value instanceof String) {
            String str = (String) value;
            if (str.isEmpty() || "null".equals(str)) {
                return null;
            }
        }

        return toLongValue(value);
    }
decimal is integer, check has non-zero small

@param decimal
@return
core/src/main/java/com/alibaba/fastjson2/util/TypeUtils.java