NEW ISSUE: Support error handling in RequestSecurityToken extension mechanism

[cyc@us.ibm.com]

Regarding to WS-Trust, at link:
http://www.oasis-open.org/apps/org/workgroup/ws-sx/download.php/16288/ws-trust-1.3-spec-ed-01-r03-diff.pdf

Title: Support error handling in RequestSecurityToken extension mechanism

Description:

The extension mechanism in the RequestSecurityToken and the RequestSecurityTokenResponse require the recipient fault if an attribute or an element is found that is not understood.   The recipient can be required to return the attribute(s) or element(s) that it doesn't understand in defined format in the fault message.  The error information can help cross vendor interoperability and even among different versions of the same vendor implementation.  An implementation potentially can fall back to a mode of operation that does not use new extensions.

Proposed Solution:  The recipient returns attribute name(s) and element name(s) that it doesn't understand in the fault message.