After five years of developer perseverance, generics are finally being added to the Java language. The path to generics has been frustrating and controversial to say the least. At JavaOne's ...

The universal generics plan promotes having generic APIs directly support primitive value types, for operating directly on custom-defined primitives. Reference types also would be supported.

The generics get plainly transfered over from Java to JS, keeping the Function type instead of Function_. Then it is actually impossible to call setAttribute(ItemAttributes.USING_MESSAGE, someinput => ...