Partly based on https://github.com/scala/scala-collection-compat/blob/master/compat/src/main/scala-2.11_2.12/scala/collection/compat/PackageShared.scala
but reproduced here so we don't need to add a dependency on this library. It contains much more than we need right now, and is
not promising binary compatibility yet at the time of writing.
INTERNAL API
Partly based on https://github.com/scala/scala-collection-compat/blob/master/compat/src/main/scala-2.11_2.12/scala/collection/compat/PackageShared.scala but reproduced here so we don't need to add a dependency on this library. It contains much more than we need right now, and is not promising binary compatibility yet at the time of writing.