Use '? super A' for Function parameter in Promise.map and Promise.flatMap

[tombeck]

It's currently not possible to call 'map' or 'flatMap' on a Promise of type Promise<? extends A>.

Changing the signature from

    public <B> Promise<B> map(final Function<A, B> function) 

to

    public <B> Promise<B> map(final Function<? super A, B> function)

would solve the issue without breaking existing code.
'flatMap' should be changed accordingly.

[jroper]

Absolutely this should be done, but we are looking at replacing the Java Promise API with the Scala Future API plus some of the sugar from Akka futures for working with futures with Java. That will resolve this issue.

[tombeck]

Is there a deadline for that change?

[jroper]

We should revisit this now that we've decided to stick with F.Promise a little longer.