question about scala / sbt contributions to universe

[Thomas Finneid]

Hi

I am looking into upgrading the scala package to the newest scala 2.12.8 
and creating a new package for the scala build tool, Sbt, 1.2.

I have been discussing this with the Debian-java team, but since scala 
must be built with the previous version of scala and sbt, and the same 
for sbt, the compile graph becomes cyclic.

One solution to this is to include in the source package a previously 
built base compilation, to help build the current version sbt and scala. 
i.e. if one wants to build sbt 1.2.9, the src package would contain a 
downloaded version of 1.2.8. And the same for scala. Its a conundrum.

In the Debian main archive, this is not allowed. I have not gotten an 
answer about wether its allowed in the contrib arhcive yet.

My question to the Ubuntu Motu team is, whether there are any such 
restrictions in the universe archive?

Regards

Thomas