Kafka 0.8 and trunk by default have SBT set up to cross-compile 2.8.0, 2.8.2, 2.9.1 and 2.9.2, and it defaults to 2.8.0.
I assume that one of the major contributors requires 2.8.0. Any approximation on how long will that last? Dropping 2.8.0 would be beneficial because some uses of Java Conversions is replaced with Java Converters (in 2.10 +), and Java Converters was not added until 2.8.1. http://stackoverflow.com/questions/8301947/what-is-the-difference-between-j avaconverters-and-javaconversions-in-scala https://issues.apache.org/jira/browse/KAFKA-717 is attempting to add build support for Scala 2.10. The required changes to support 2.10 use Java Converters, which is not available in 2.8.0. The other item required to support Scala 2.10 is to move from scala.StaticAnnotation to scala.annotation.StaticAnnotation. Scala 2.10.x has only scala.annotation.StaticAnnotation. Scala 2.9.x has both scala.StaticAnnotation (deprecated) and scala.annotation.StaticAnnotation. Scala 2.8.x has only scala.StaticAnnotation Dropping support for 2.8.x entirely and supporting only 2.9.x and 2.10.x would make 2.10.x support easy. If 2.8.2 is required (but not 2.8.0), then some sort of conditional compile or two flavors of the source code where scala.annotation.StaticAnnotation is used will be required. Use of StaticAnnotation is very limited. If 2.8.0 must be kept, then two versions of all code that uses Java Conversions APIs will also need to be maintained. I can't find any discussions about 2.8.0 usage requirements. I also don't know enough about sbt to configure cross compilation to use different source files for different cases, which would solve the problems above but add some maintenance burden.
