Idp v3 external auth -- changes from v2 idp

[C G]

Dear IDP gurus

Finally our team decided to move to idp v3. Currently at v2.3 idp.
Our sys has external auth integrated but in one war file as shib IDP as per 
http://shibboleth.1660669.n2.nabble.com/Forwarding-authentication-request-error-404-ExternalAuth-SOLVED-tp7310618p7316204.html

It is working awesomely ;  let's call this v2ea


Now as I read specs for v3 it says on AuthnMethod from 
https://wiki.shibboleth.net/confluence/plugins/servlet/mobile#content/view/17072294

authnMethod (deprecated)	String	Identifier for an authentication method supported by the flow
Use of "authnMethod" is deprecated because login flows in V3 are more general than in V2 and are designed to handle more than one possible method at a time, so the full semantics of a request can only be understood by examining the profileRequestContext. The value in this attribute will generally be an arbitrary one chosen from among the possible set that the flow is configured to support. To determine whether the RP requested a specific form of authentication, you must walk the context tree from the root down to the AuthenticationContext and then on to a RequestedPrincipalContext.


Now my q: can some pls point me to right changes needed from v2ea  integration ? 

Again single war file bundled here : ( if it matters we use struts2 for ea)

Thanks in anticipation

Best 
CG


Excuse me for brevity and typos from iPhone Keypad!
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