aact-615: prevent error if a data value is missing.  Add method to provide list of users.
aact-615: prevent error if a data value is missing.  Add method to provide list of users.
tibbs001/aact-1,ctti-clinicaltrials/aact,tibbs001/aact-1,ctti-clinicaltrials/aact,ctti-clinicaltrials/aact,tibbs001/aact-1