fix #11465: properly populate roles proxy object

http://hudson.openmicroscopy.org.uk/job/OmeroJava-integration-develop/lastSuccessfulBuild/testngreports/integration/integration.AdminServiceTest/ should all pass and the graying-out of https://github.com/openmicroscopy/openmicroscopy/pull/1753#issuecomment-29200601 should work.