public Item withNumberSet(String attrName, Number ... vals) {
        checkInvalidAttribute(attrName, vals);
        Set<BigDecimal> set = InternalUtils.toBigDecimalSet(vals);
        if (set.size() != vals.length)
            throw new IllegalArgumentException(DUPLICATE_VALUES_FOUND_IN_INPUT);
        return withBigDecimalSet(attrName, set);
    }
Sets the value of the specified attribute in the current item to the
given value.
aws-java-sdk-dynamodb/src/main/java/com/amazonaws/services/dynamodbv2/document/Item.java