Avroparquet: Lower bound higher kinded

[paualarco]

Hello!
There is no issue related with this PR.

While looking at how to implement protobuf parquet connector, I realised that the current implementation of avroparquet was statically typead as GenericRecord, which for the Akka user is not nice.

On continuation with that the tests were simplified and improved by not just checking the number of records written but also the actual content of the file.

[paualarco]

I have noticed that it breaks the site creation with paradox, once I got some feedback I would fix that by creating a new test to support that.

[ennru]

Thank you for this PR. I rebased it (as we had some problem with tests not running), fixed Paradox and added the required Mima exclusions.

Please improve the docs and examples to show that you may use a more specific type than Generic Record now.

We plan to release Alpakka 2.0 next week, it would be great to get this in.

[paualarco]

Thank you for this PR. I rebased it (as we had some problem with tests not running), fixed Paradox and added the required Mima exclusions.

Please improve the docs and examples to show that you may use a more specific type than Generic Record now.

We plan to release Alpakka 2.0 next week, it would be great to get this in.

Have pushed the changes, note that I have only added a scala example that will demonstrate the improvement, and I have explicitly mentioned that in the documentation.
Hope it will be enough for now :)

I think that for the time being this is a good improvement, but still could be even better to completely erase the type constrain on GenericRecord, in which therefore any implementation of ParquetWriter or ParquetReader could be used and not just the Avro one.

Sadly I have not the time to implement it at that moment, but I will in the future if no one does... that would also imply a wider test coverage as well as renaming the whole sub-module.

[ennru]

Thank you, I've pushed some updates as I'd like to see the PR for the release.

[ennru]

LGTM.