Description
In Spark 2.0, `DataFrame` is an alias of `Dataset[Row]`. MLlib API actually works for other types of `Dataset`, so we should accept `Dataset[_]` instead. It maps to `Dataset<?>` in Java. This is a source compatible change.
In Spark 2.0, `DataFrame` is an alias of `Dataset[Row]`. MLlib API actually works for other types of `Dataset`, so we should accept `Dataset[_]` instead. It maps to `Dataset<?>` in Java. This is a source compatible change.