Duplicate CacheKey with several query parameters value on null (IBATIS-663)

[Fernando Carballo]

I'm having a problem with cached stored procedures call, using null
parameters.
When I call a stored procedure like: "call user.some_sp(?,?)" I get the same
cacheKey for parameters: [1, null] and [null, 1]
I think that the problem is in class
com.ibatis.sqlmap.engine.exchange.BaseDataExchange on method getCacheKey:
for (int i = 0; i < data.length; i++) {
      if (data[i] != null) {
        key.update(data[i]);
      }
}
If the paramValue is null, it is ignored. Then when I get the cacheKey, on
the parameters
 values part, I get |1| for both parameters pair.