public static Object extractSingleValue(Map<?, ?> value) {
        if (value == null || value.size() != 1) {
            throw new IllegalArgumentException(ERROR_SINGLETON_MAP + value);
        }

        return value.values().iterator().next();
    }
Extract one and only value from singleton map - key will be ignored.

@param value singleton map
@return value
@throws IllegalArgumentException if the given map is null or contains zero or
                                 more than one element
clickhouse-data/src/main/java/com/clickhouse/data/ClickHouseValues.java