fix(go/adbc/driver/internal/driverbase): proper unmarshalling for ConstraintColumnNames

[zeroshade]

Fixes #2278

The current UnmarshalJSON function for requiredList ended up unmarshalling into a copy of the underlying slice rather than using the actual slice, so the data wasn't being propagated appropriately. This fixes the UnmarshalJSON function to handle the scenario appropriately.

[zeroshade]

CC @davidhcoe Can you confirm that this fixes the issue reported?

[davidhcoe]

This doesn't work for me. I put together a sample to test with based on the result I get from Snowflake:
sf_results.json

func (suite *SnowflakeTests) TestJsonUnmarshal() {
   jsonFile, err := os.Open("sf_results.json")
   if err != nil {
   	log.Fatal("Failed to open file:", err)
   }
   defer jsonFile.Close()

   byteValue, err := ioutil.ReadAll(jsonFile)

   var getObjectsCatalog driverbase.GetObjectsInfo
   if err := json.Unmarshal(byteValue, &getObjectsCatalog); err != nil {
   	log.Fatal("Failed to parse JSON:", err)
   }

   for i, sch := range getObjectsCatalog.CatalogDbSchemas {
   	for j, tab := range sch.DbSchemaTables {
   		for k, con := range tab.TableConstraints {
   			for l, _ := range con.ConstraintColumnNames {
   				fmt.Println(getObjectsCatalog.CatalogDbSchemas[i].DbSchemaTables[j].TableConstraints[k].ConstraintColumnNames[l])
   			}
   		}
   	}
   }
}

[zeroshade]

@davidhcoe I've updated the PR and added a test based on your example. Can you confirm it works for you?

[davidhcoe]

Yes -- it works for me now. Thank you.

[joellubi]

Good catch with the non-pointer receiver, thanks!