Add metadataFormatIsEmpty in TarantoolTuple

[ArtDu]

It's needed when we expected crud and box responses by one mapper(AUTO mapper in cartridge-springdata). In case when we obtain box response and we didn't have prepared metadata from ddl/_vspace, we can't map these values to Entity without metadata and we can't check whether we have it or not. And we can't raise an exception that we don't have metadata before because we can take it from crud response. Springdata doesn't see a difference between crud and box responses, it only got TarantoolTupleResult

I haven't forgotten about:

• Tests
• Changelog
• Documentation
• Commit messages comply with the guideline
• Cleanup the code for review. See checklist

Related issues:
Needed for tarantool/cartridge-springdata#123

[akudiyar]

This change is OK by itself, just some wording and naming needs to be fixed.

But there is a greater question, do we need this change at all. It seems it is not comfortable to work with a tuple that represents in fact two different entities.

Could it be better if we derive a TarantoolTupleWithMetadata interface from the original TarantoolTuple one, move to the second one all methods that access fields by names, add the corresponding *Impl class, and then use that interface distinction in SpringData via instanceof? That will allow us to finally avoid all the checks for metadata presence that we have to use in current implementation, and the user confusion when they try to get a field by name and see a strange "metadata does not exist" error.
With that implementation, we can change the *Proxy* API classes to return TarantoolTupleWithMetadata tuples instead of TarantoolTuple ones. That may also probably require changing the TarantoolTuple interface somewhere either to Packable or to ? extends TarantoolTuple.

[akudiyar]

I suggest using a simpler naming like hasMetadata or isMetadataEmpty

[ArtDu]

Renamed to hasMetadata

[ArtDu]

Added ticket about splitting TarantoolTuple class to use for input and output(with/without metadata)

#375

[akudiyar]

I still have the same question, see below

[akudiyar]

If we are going to use different types (TarantoolTuple and TarantoolTupleWithMetadata). do we really need this method then? It is a public API, we need to carefully think before changing it

[ArtDu]

We'll break compatibility anyway. So I don't see a big problem to have hasMetadata now and then remove it. I want to sync springdata and cartridge-java as soon as possible, because we've already been being late

[akudiyar]

We need to change this entry too

[akudiyar]

OK. Let's amend this change in the nearest updates then.