Merge two attributes in Shibboleth v3

[Peter Schober]

* Peter Schober <peter.schober at univie.ac.at> [2018-03-17 15:38]:
> * Rod Widdowson <rdw at steadingsoftware.com> [2018-03-17 15:27]:
> > You need to do some reasonably weird stuff with dependencies and
> > sourceAttributeID.  Read [1] the section on Multi-Attribute
> > Dependencies (and beware that this will all be deprecated in 3.4
> > where the same stuff will be possible, but the code will be more
> > obvious.
> 
> No. A template definition with the urn string prefix set in a
> template, and a single attribute from LDAP as dependency.
> That's all. Nothing weird.

Of course you were providing the literal answer to the question in the
subject. That is slightly weird in v3, though mostly because of the
resulting when having differing attribute names from different
dependencies, whicjh can be silenced via logback.
-peter