add support all types dataSource

[stepanovD]

Hello. This pull request includes support for all types of datasource (table, union, query). It's nice feature for support subquery as datasource. I understand, this change breaking backward compatibility, but it's very important feature. May be adding this change in 3.0 release is better.

[stepanovD]

Hello. What you think about this pull-request?

[GG-Zapr]

Hi @stepanovD, We are out this week. Would look into it once we are back

[stepanovD]

Hi. Are you planning to add this changes in future releases?

[abhi-zapr]

+1

[abhi-zapr]

No comments 👍
But implement this few points :

• Reformat code if indentation is not equal everywhere. If you are using IntelliJ to code, you can use this style guide.
  https://s3-ap-southeast-1.amazonaws.com/zapper-static-data/intellij-java-google-style.xml

• For newly added classes add Copyright in every file (apart from README.md) if not already added.

Thank you.

[abhi-zapr]

Hi. Are you planning to add this changes in future releases?

Hey @stepanovD

Sorry for the delay. Yes are definitely planning to add these changes in future release. As you yourself said, these are the breaking changes so we can plan to add these in 3.0 release. But there are few patches that we are planning to release in 2.x and then we can release this patch.

[stepanovD]

• Reformat code if indentation is not equal everywhere. If you are using IntelliJ to code, you can use this style guide.

Reformat code is done! Copyright already added.