Let me quote the xtext2 reference section Customized Post Processing
As a last step, the generator invokes the post processor for every generated Ecore model. The post processor expects an Xtend1 file with name MyDslPostProcessor.ext (if the name of the grammar file is MyDsl.xtext) in the same folder as the grammar file.
So I can use xtend2 files in post processing? Thanks!
By the way Eclipse help contains Xtend content, no mention of xtend1/xtend2 which is kind of misleading.