Serialization opt-in syntax (again)

[Brian Goetz]

>> I'm sorry that I'd forgotten this _ suggestion before. I like it.
> 
> We talk about _ as an identifier, not as a placeholder for a type.

What we talked about was removing _ from the space of identifiers, so that it could be used for something else.  Using it as a placeholder for a type was one of the possible uses offered.  

> Brian, I suppose that you can use '_' everywhere the inference is used,
> so Array.<_>asList(2, 3) is also legal ?

That would be consistent with the possible future use of _ as an "infer me" token that I alluded to in my earlier message.