[incubator-kie-issues#1627] Change log level from error to debug inside ImportDMNResolverUtil

[yesamer]

Closes apache/incubator-kie-issues#1627

Follow up of #6150, discovered during apache/incubator-kie-issues#1627 testing.

Based on the current architecture, the resolveImportDMN(Import, Collection<T>, Function<T, QName>) is called twice, which means that an error logged in the first call is inconsistent with the second call, where the behavior works as expected.

As a consequence, all log levels should be set as DEBUG, until a definitive fix in the architecture.

[gitgabrio]

Hi @yesamer
on second thought, I think we have to change the overall approach here.
That method get's invoked twice, once with an empty Collection<T> dmns and once with a populated one.
The "misleading" logs are related to the first one.
So, I think it is better that, when an empty dmns collections is recieved, the method immediately returns back with an Either.of left, and debug messaging explaining it.
If, instead, a populated collection is received, all failures on finding imported model should be logged as error: wdyt ?

[yesamer]

@gitgabrio The improvement you suggested makes sense, but I would manage it in this ticket apache/incubator-kie-issues#1383 (please feel free to update it) and provide a complete refactoring of the feature

[gitgabrio]

@yesamer
The ticket you mention has a more broader impact and it is not sure when it could be done.
On the other side, reviewing this PR, I realized that we are dealing two different uses cases (empty or populated dmns) with the same logic.
In one case, the "error" level is required, but now (even with my previous one) we are logging everything as debug, which is wrong, IMO.
Since it is just a matter of a couple of lines in the very same method already touched by this PR, I think it would be better to fix that with this PR (and reverting the "debug" messages to "error").

[yesamer]

@gitgabrio Done, thank you

[gitgabrio]

Thanks @yesamer
lgtm!

[yesamer]

@baldimir Can you please review it?