Hello, I saw that there are several TODOs to migrate some transformers (like HashingTF and IDF) to use only ml.Vector in order to avoid the overhead of converting them to the mllib ones and back.
Is there any reason why this has not been done so far? Is it to avoid code duplication? If so, is it still an issue since we are going to deprecate mllib from 2.3 (at least this is what I read on Spark docs)? If no, I can work on this. Thanks, Marco
