public static Type getMapValueType(Type fieldType) {
        if (fieldType instanceof ParameterizedType) {
            ParameterizedType parameterizedType = (ParameterizedType) fieldType;
            Type[] actualTypeArguments = parameterizedType.getActualTypeArguments();
            if (actualTypeArguments.length == 2) {
                return actualTypeArguments[1];
            }
        }
        return Object.class;
    }
decimal is integer, check has non-zero small

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