Please describe the problem:
Doxygen does not appear to add any information about whether Objective-C 2.0 protocol methods have been marked as @optional or @required to its XML output.

This information is added to the generated HTML files, but there does not seem to be any way to determine whether a protocol method is optional or required solely from the XML output. This makes it very difficult to write XSLT stylesheets to format the XML however one wants -- no matter what, the information available from the XML is not as complete as that in the HTML output.

Steps to reproduce:
1. Mark protocol methods as @optional or @required
2. Generate XML documentation
3. Look for any indicators as to required-ness in the generated XML


Actual results:
There is no way to determine whether a given member of the protocol is optional or required.

Expected results:
Each member has a "required='yes/no'" attribute or something similar.

Does this happen every time?
yes

Other information:
I maintain a script (called Doxyclean) which converts Doxygen's XML output into a format which is consistent with Apple's documentation. Without this information, my script is unable to mark protocol methods appropriately.