getPrincipals() typing

[Klingenstein, Nate]

> I don't know what else you're after. The APIs are not ours, they're part of
> Java and should be documented reasonably well.

Constraints that you can't impose, evidently.

> about. There are no semantics at the level of Principal or Subject.

Yeah, that was what I was after.  There are no semantics or constraints anywhere.  I'm still mystified that I can call the Password flow as a subflow without modification.  What are the flow execution keys even relative to?  I'll figure that out next.

This is the whole "where is the entrance" and "where is the exit" stuff.  Tom Zeller guessed what I meant.

There basically is no entrance nor exit.  There's basically no state anywhere.

> > I get null if I don't specify a principal type.
> > result.getSubject().getPrincipals().iterator().next().getName();
> 
> I don't think that's possible unless we have a Principal class that's returning
> null there, and I'm not sure we do

I don't know definitively that it was null.  It wasn't barfing, and it did barf if I didn't set a static type for UsernamePassword (e.g. trying to literally use "UsernamePassword" or "UsernamePassword.class" without a T).  I did log the results and got an apparently null string and "something" got shipped to the browser, but I didn't figure out how to log things in the browser meaningfully yet.

That development="true"

    <webflow:flow-builder-services id="flowBuilderServices" view-factory-creator="mvcViewFactoryCreator" development="true" />

to try to reload the flows is pretty much... not awesome.  If I didn't have to spend a minute and a half between tests, this wouldn't be Wednesday.