Entity Attribute Data Connector

[Rod Widdowson]

> I didn't follow why this would be a data connector or what the injected
> strategy would be used for, 

I'm not wedded to the idea of a data connector, indeed I'm just of a call to
Tom where I indicated some of the nastiness involved.  This is mostly
because a DataConnector produces a Map<String, Attribute> and we need to
produce a Map<String, RequestedAttribute> in the ACS case.  But there is a
lot of stuff which has no real use in this situation.

It just seemed like a useful bit of code re-use which might have application
elsewhere and later.  When it comes to it I need to produce an Identifiable,
InitializableClass that has a method which takes a Context (of some sort)
and returns either a List< T extends Attribute> or, more likely a
Map<String, T extends Attribute>.

> What is the function from the context to List<XMLObject> doing?

Basically I do not want to this code to have to traverse the
AttributeFilterContext to get the List of (SAML) Attributes or
RequestedAttributes, and I would like to be able to use this code in other
situations (like AttributeQuery, but possibly other situations).    So as
usual I punted to an indirection and assumed a strategy Function which will
take on the heavy lifting of (in the ACS case), finding the SP Metadata,
finding the ACS for this request, and calling #getRequestedAttributes().  In
the AttributeQuery case it would traverse the (SAML) Message and find
AttributeQuery, and thence call  #getAttributes().

Hence the List<XMLObject>, although List<[SAML2]Attribute> would also do the
trick.

/Rod