write xmlrpc function updateWhiteboard that is to be contributed to the upstream. Please refer to the following url for details on Bugzilla::RPC 2.18 functions mapped to upstream Bugzilla::WebService and for 2.18 xmlrpc functions sorted by percentage of calls: https://engineering.redhat.com/trac/bugzilla-3.0-rh/wiki/XmlrpcCrossComparison#a2.18xmlrpcfunctionssortedbypercentageofcalls
updateWhiteboard is not one of the functions that were required to be ported to the compat_xmlrpc temporary API, and its functionality can be achieved with current 3.2 WebService function Bug.update. so closing bug.