HttpClient parameterization

[Rod Widdowson]

We came to a closure on this on Friday but I cannot completely fathom my notes, so I'm hoping someone will fill me in.  My apologies
for dropping that ball.

- I'll complete the refactoring that I started in IdP 680
- We move all defaults down to java-support, suitably named (so not "Dynamic Metadata", but "small download", or some such)
   But I forget precisely how we decided to do so.  I have a memory of there being some sort of enumeration for the defaults?  Can
someone help me out?

/Rod